msm: smsm: Use interrupt mask for local SMSM notifications

Only trigger SMSM callback processing for the local processor if
callbacks have been registered.

Without this fix, excessive SMSM bit toggles may overflow the SMSM
snapshot queue.

Change-Id: Ieeb3e62f50915807eae92ac0762b2af5ac8a8438
CRs-Fixed: 378402
Signed-off-by: Eric Holmberg <eholmber@codeaurora.org>
Signed-off-by: Angshuman Sarkar <angshuman@codeaurora.org>