msm: vidc: Increase output buffer count for DCVS

To get more residency at lower voltage corner, buffer count needs
to be increased for resolutions for which DCVS is enabled. This
change lowers the power consumption during video playback of higher
resolutions but at the cost of increase in memory.

Change-Id: I2d0adc5e0483bba5c4f4dd6d0070ef8a518a3597
Signed-off-by: Vinay Kalia <vkalia@codeaurora.org>