ima: re-initialize IMA policy LSM info

Although the IMA policy does not change, the LSM policy can be
reloaded, leaving the IMA LSM based rules referring to the old,
stale LSM policy.  This patch updates the IMA LSM based rules
to reflect the reloaded LSM policy.

Reported-by: Sven Vermeulen <sven.vermeulen@siphos.be>
tested-by: Sven Vermeulen <sven.vermeulen@siphos.be>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: Eric Paris <eparis@parisplace.org>
Cc: Casey Schaufler <casey@schaufler-ca.com>