msm: camera: isp: Add debugfs parameter for state monitor dump

This change adds a debugfs parameter to enable isp context state
monitor dump rather than always print by default. This change
also changes isp context substate to HALT only after stop hw
is complete.

Change-Id: I1025a46e9be63b4ee5808c2eb44672687d901c2e
Signed-off-by: Venkat Chinta <vchinta@codeaurora.org>