msm: tspp2: Fix handling of context-based counters

TSPP2 HW maintains various statistics counters. These HW counters are
based on the context index rather than the filter HW index. Fix the driver
to use the appropriate index when dispaying the counters in debugfs and
when resetting the counters.

Change-Id: I2098bf5fd936ca9f1a136b925da2f7998b8c0c96
Signed-off-by: Liron Kuch <lkuch@codeaurora.org>