##### SUMMARY
If you pass aws_kms an existing key_id and no alias, it throws exceptions

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
lib/ansible/modules/cloud/amazon/aws_kms.py

##### ANSIBLE VERSION
```
ansible 2.8.2
  config file = /home/mchappel/.ansible.cfg
  configured module search path = [u'/home/mchappel/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python2.7/site-packages/ansible
  executable location = /usr/bin/ansible
  python version = 2.7.5 (default, Jun 11 2019, 12:19:05) [GCC 4.8.5 20150623 (Red Hat 4.8.5-36)]
```

##### CONFIGURATION
```
DEFAULT_CALLBACK_WHITELIST(/home/mchappel/.ansible.cfg) = [u'timer', u'profile_tasks']
DEFAULT_VAULT_IDENTITY_LIST(/home/mchappel/.ansible.cfg) = [u'original@/home/mchappel/.ansible/secrets/original', u'ssl@/home/mchappel/.ansible/secrets/ssl', u'jenkins@/home/mchappel/.ansible/secrets/jenkins']
HOST_KEY_CHECKING(/home/mchappel/.ansible.cfg) = False
RETRY_FILES_ENABLED(/home/mchappel/.ansible.cfg) = False
```

##### OS / ENVIRONMENT
RHEL7

##### STEPS TO REPRODUCE
```
     - name: Update Policy on key to match AWS Console generate policy
       aws_kms:
        key_id: '{{ new_key["keys"][0]["key_id"] }}'
         policy: "{{ lookup('template', 'console-policy.j2') | to_json }}"
       register: kms_policy_changed
```

##### EXPECTED RESULTS
Key successfully updated


##### ACTUAL RESULTS
Exception.  (There's actually a couple of places that need updating)


##### ADDITIONAL DETAILS
@willthames 

https://github.com/tremble/ansible/tree/aws_kms_keyid_only contains updated tests and a fix.  I'll submit a PR once we know what order everything's likely to get merged in.  Side effect of the change, aws_kms is substantially faster, as a result I had to more the iam_role creation in the test suite.
ret = {}
    keyret = kms.get_key_policy(KeyId=keyarn, PolicyName='default')
    policy = json.loads(keyret['Policy'])
    changes_needed = {}
    assert_policy_shape(policy)
    had_invalid_entries = False
    for statement in policy['Statement']:
        for granttype in ['role', 'role grant', 'admin']:
            
            
            
            if not isinstance(statement.get('Principal'), dict):
                statement['Principal'] = dict()
            if 'AWS' in statement['Principal'] and isinstance(statement['Principal']['AWS'], string_types):
                
                statement['Principal']['AWS'] = [statement['Principal']['AWS']]
            if not isinstance(statement['Principal'].get('AWS'), list):
                statement['Principal']['AWS'] = list()
            if mode == 'grant' and statement['Sid'] == statement_label[granttype]:
                
                if granttype in granttypes:
                    invalid_entries = [item for item in statement['Principal']['AWS'] if not item.startswith('arn:aws:iam::')]
                    if clean_invalid_entries and invalid_entries:
                        
                        
                        valid_entries = [item for item in statement['Principal']['AWS'] if item.startswith('arn:aws:iam::')]
                        statement['Principal']['AWS'] = valid_entries
                        had_invalid_entries = True