ima: Fix documentation-related warnings in ima_main.c

Fix the following warnings in ima_main.c, displayed with W=n make argument:

security/integrity/ima/ima_main.c:432: warning: Function parameter or
                          member 'vma' not described in 'ima_file_mprotect'
security/integrity/ima/ima_main.c:636: warning: Function parameter or
                  member 'inode' not described in 'ima_post_create_tmpfile'
security/integrity/ima/ima_main.c:636: warning: Excess function parameter
                            'file' description in 'ima_post_create_tmpfile'
security/integrity/ima/ima_main.c:843: warning: Function parameter or
                     member 'load_id' not described in 'ima_post_load_data'
security/integrity/ima/ima_main.c:843: warning: Excess function parameter
                                   'id' description in 'ima_post_load_data'

Also, fix some style issues in the description of ima_post_create_tmpfile()
and ima_post_path_mknod().

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Link: https://lore.kernel.org/bpf/20220302111404.193900-2-roberto.sassu@huawei.com