msm: lmh_lite: re-enable lmh interrupt only during polling

There is a possibility that lmh driver will receive interrupts for
back to back short lived hardware throttling condition. Re-enable
interrupt only in polling mode handler to mitigate the impact of
these zero intensity reporting hw throttling conditions.

Change-Id: I938e481b525112c84b0a35648ef0fb730b35c4a4
Signed-off-by: Ram Chandrasekar <rkumbako@codeaurora.org>