msm: pil: Add module parameter to override proxy vote timeouts

For debugging purposes, it's sometimes useful to disable or adjust
proxy vote timeouts. Add a module parameter for this purpose.

If proxy_timeout is set to 0, proxy votes will remain asserted until
the peripheral is shutdown. If it's set to a positive value, the value
will be interpreted as override (in ms) for all proxy timeouts. The
default value (-1) will cause the timeout specified in the individual
PIL drivers to be used.

Change-Id: I74a111b8e4e62a15e01c4e2480b7127e84b9f467
Signed-off-by: Matt Wagantall <mattw@codeaurora.org>