perf: llcc: Fix the mask to clear and disable the LLCC PMU

The mask to clear the counters and to disable the monitor
seems to be incorrect. Fix the masks so that monitor is
properly disabled and saturated status of the counters is
cleared after they are read.

Change-Id: If3a999c92727ba05fbe4dbfa89b1aae41d3b78dc
Signed-off-by: Rama Aparna Mallavarapu <aparnam@codeaurora.org>