ima: Fix function name error in comment.

The original function name was ima_path_check().  The policy parsing
still supports PATH_CHECK.   Commit 9bbb6cad ("ima: rename
ima_path_check to ima_file_check") renamed the function to
ima_file_check(), but missed modifying the function name in the
comment.

Fixes: 9bbb6cad ("ima: rename ima_path_check to ima_file_check").

Signed-off-by: Jiele Zhao <unclexiaole@gmail.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>