msm: camera: isp: handle drop frame if the pattern is valid

If the framedrop pattern is valid, and if we reload wm,
frame starts to output from the point of reload wm itself.
Drop the frame, if frame drop pattern is valid.

Change-Id: If93d875032d6ac876a4cefe349fdd6aab1980f9e
Signed-off-by: Senthil Kumar Rajagopal <skrajago@codeaurora.org>