smp: enhance power efficiency

Here we are trying to reduce power usage through the
use of macros cpu_relaxed_read_short and cpu_relaxed_read.

Bug 1440421

Change-Id: I114d122cf58b1cf7b93b4b5f5d712360a2f1e096
Signed-off-by: Sumit Singh <sumsingh@nvidia.com>
Reviewed-on: http://git-master/r/425947
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Sri Krishna Chowdary <schowdary@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Alexander Van Brunt <avanbrunt@nvidia.com>

Conflicts:
	kernel/smp.c