msm: spm_devices: Check for L2 SPM's core id

The L2 SPM device was being set incorrectly if the core-id was not in
the range of the supported CPUs. The DT for certain devices are shared
among cores that have different CPUs. In cases where the core-id didn't
match the physical core, it was being incorrectly set to L2 and causing
issues when the SPM hardware was accessed.

Fix by checking for L2 core-id of 0xffff before assigning it to an L2
device.

Change-Id: I90f8d3606ddfdc4987bb4d7918e0712d28e17083
Signed-off-by: Mahesh Sivasubramanian <msivasub@codeaurora.org>