msm: pil-gss: Move to subsystem_get()/put() API

Insert a shim implementation of the subsystem framework's start
stop functions. For now, just call pil_get() and pil_put() until
all drivers are moved to start/stop functions.

Change-Id: I3578fec9b1a6234700efb0c3b034d24377700080
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>