msm: pil: Warn if proxy_timeout is set to 0 ms

A proxy vote set to expire in 0 ms is never reasonable and just indicates
the desc->proxy_timeout was never set. Warn if this is detected to make
such mistakes easier to catch.

Change-Id: Ibbe7437c3120f6af6aa37217f380b350a1ff2a06
Signed-off-by: Matt Wagantall <mattw@codeaurora.org>