msm: lmh_lite: Make LMH intensity polling a high priority

Add support for a new high priority workqueue to post
all the LMH polling work. This ensures that the LMH
poll work executes in high priority, which indirectly
ensures that intensity change notifications are sent
without much delay.

CRs-Fixed: 900507
Change-Id: I8670a68c83183288d674b0cf75f7da2744cbf86b
Signed-off-by: Ram Chandrasekar <rkumbako@codeaurora.org>