platform: msm_shared: modify prefetch start lines
platform: msm_shared: modify prefetch start lines

Current code enable prefetch only if the vertical
back porch is less than 9 lines. This change
modifies the behavior to enable prefetch if the vertical
back porch plus the vertical pulse width is less
than 25 lines, so we can have more margin of vertical
timing for prefill.

Change-Id: Idb0eb1d0894ec3cec10cf733ffcba88f6c8e4219

CanarySolutions/little-kernel,efidroid/lk,CanarySolutions/little-kernel,CanarySolutions/little-kernel,efidroid/lk,efidroid/lk,efidroid/lk,CanarySolutions/little-kernel,efidroid/lk,CanarySolutions/little-kernel