msm: kgsl: Allow non-default timeout values in adreno_idle

In adreno_idle the default timeout value was always used,
even if the caller specified something different. The caller
can now specify a non default timeout value to be used
in adreno_idle.

Change-Id: Ibb6bcc094521d4a660d8385b32bf8c6ac68acbd9
Signed-off-by: Tarun Karra <tkarra@codeaurora.org>