ima: fix the string representation of the LSM/IMA hook enumeration ordering

This patch fixes the string representation of the LSM/IMA hook enumeration
ordering used for displaying the IMA policy.

Fixes: d9ddf077 ("ima: support for kexec image and initramfs")
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Tested-by: Eric Richter <erichte@linux.vnet.ibm.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>