spm: Rename spm-v2 to spm

spm-v2.c (v2 stands for version 2) currently is SAW version 2 specific.
Going forward we need to support version 3 as well. Make this file generic
to all the versions.

Change the CONFIG name to be consistent with file name.

Change-Id: Ia635e8e9dee96b28339f2ec89914274f915d25f6
Signed-off-by: Archana Sathyakumar <asathyak@codeaurora.org>