msm_fb: Set timeline threshold for command mode to 2

For command mode panel, timeline threshold is 1 and we return
commit ioctl on DMA_P interrupt. This causes fps to drop
since sometimes overlay is kickoff just after vsync interrupt
causing DMA_P wait time more than 1 vsync period. Hence, increase
timeline to 2 and return commit ioctl on vsync interrupt.

CRs-fixed: 457153
CRs-fixed: 452269
Change-Id: Ic7385631fdeb25f269306d284c94fdf43cade3d1
Signed-off-by: Padmanabhan Komanduru <pkomandu@codeaurora.org>