Revert "msm: gdsc: Increase GDSC enable/disable timeout to 1 ms"

The root cause of timeouts had been addressed in commit 8a2898925,
"iopoll: Make readl_poll_timeout() and friends preemption-safe"
and so the increased 1 ms timeout is no longer needed. Decrease it
back to 100us so that errors are printed if any GDSCs take longer
than expected to enable.

Change-Id: I20ca6fac64b9d8b05fb29227e22dce3d7136611a
Signed-off-by: Matt Wagantall <mattw@codeaurora.org>