msm: vidc: Set DPB count to firmware during split mode

Previously driver never used to set DPB count to firmware.
Based on new firmware changes for internal buffer size
calculation now it is mandatory to set buffer counts for
DPB. Hence, set DPB count for split mode.

Change-Id: I2e8a13f5c5c1566716658167854c6ba969e0c8a9
Signed-off-by: Vaibhav Deshu Venkatesh <vdeshuve@codeaurora.org>