power: qcom: apm: add support for msm8996pro

Mutual exclusion between APM switching and LMH register accesses
is only required for HMSS version 1.2 and below on MSM8996.  It
is not required for HMSS version 1.2 on MSM8996-Pro.  Add support
for MSM8996-Pro so that the LMH mutex is not locked during APM
switching on MSM8996-Pro parts.

Change-Id: If09454827ed12c4d436c2fc792f5adcd45ef4312
Signed-off-by: David Collins <collinsd@codeaurora.org>