msm: subsys-pil-tz: Merge scm-pas functionality in generic PIL driver

With all subsystems that need trust-zone for authentication now
tapping into the generic PIL/SSR driver, the scm-pas APIs can be
merged with subsys-pil-tz.

Change-Id: I3904eba79679ac6b44d5fd8a7c4e638a45cbe8bb
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>