msm: mdss: read active line count before triggering ESD read

In the current implementation before triggering ESD read,
DSI SW waits for extra time to skip display blanking period.
Add an additional check for active line count to ensure that
ESD read is always triggered during display active region only.

Change-Id: I5893daf7cdfb8c1d0a0e962eb2e37d7cd053a6a5
Signed-off-by: Ashish Garg <ashigarg@codeaurora.org>