msm: kgsl: Add fault count to snapshot debugfs

Additional faults can occur between when a snapshot is frozen
and the snapshot is read.  Keep track of the total number of
faults encountered to keep track of how the GPU is actually
doing on multi-hour test cases.

Change-Id: I392fce74e7d215aa7bd0e1a7ce5c9f340413cd53
Signed-off-by: Carter Cooper <ccooper@codeaurora.org>