msm: mdss: fix logic in DSI data lane overflow recovery

The DSI lane overflow recovery should be done only during
active region. Currently, we consider the vertical front
porch also to be part of minimum line count check. This needs
to be fixed since vertical front porch region arrives after
the MDP active region. Also consider the minimum line count
while checking the upper limit of the current MDP line count.

Change-Id: I02401be74ff3af303624eacae8576dd5ccada3f3
Signed-off-by: Padmanabhan Komanduru <pkomandu@codeaurora.org>