drivers: qcom: rpmh: check for invalid sleep/wake values

Sleep/Wake values when unitialized will be set to UINT_MAX. Such
requests are not sent to the TCS when flushed, they are ignored. Fix
typo in checking for INT_MAX instead of UINT_MAX.

Also, if the sleep and wake requests are the same skip writing them to
the TCS.

Change-Id: I966d856b6cdb15d271de0b93f0bbb52a98e4951f
Signed-off-by: Lina Iyer <ilina@codeaurora.org>