msm: lmh_lite: Update to threaded interrupt handling

Update the LMH interrupt to be handled in a threaded
interrupt manner. This avoids the interrupt service
routine from queuing a work event to acquire mutex and
query the hardware to handle the interrupt. Instead this
using a threaded interrupt model will allow the LMH isr
to acquire mutex, query the hardware and then decide
whether to re-enable the interrupt.

CRs-Fixed: 898980
Change-Id: Ieb15406eb076d98117470d8e7a79269fd8a257fc
Signed-off-by: Ram Chandrasekar <rkumbako@codeaurora.org>