soc: qcom: rpm-smd: Read ACKs for sleep set on wakeup

The ACKs from sleep set are not read by the driver until after the system
wakeups from suspend and interrupts are enabled. Depending on the number of
outstanding ACKs, the receive buffer could be full with sleep set ACKs and
could result in a crash if clients try to vote for active requests.

Fix by reading the ACKs from sleep set while exiting sleep before drivers
can send additional requests.

Change-Id: Id0894c9b6b637da164a5d3331d9b7e697dffd4bc
Signed-off-by: Mahesh Sivasubramanian <msivasub@codeaurora.org>