video: msm_fb: Increase display timeout to 2 seconds

One second time out for no frame update, as in current implementation,
does not allow CABL to reach minimum backlight level possible because
histograms dont get generated after one second. So increase time out
period to two seconds which seem to be sufficient for complete black to
complete white and vice versa transitions.

CRs-Fixed: 370804
Change-Id: I0712924d669abcb820654cd6ca5f7da37bed57e6
Signed-off-by: Pravin Tamkhane <pravint@codeaurora.org>
Signed-off-by: Carl Vanderlip <carlv@codeaurora.org>