msm: vidc: Skip resetting skip_pc_count for SYS_PC_PREP cmd

Video driver is not raising sys_error if video firmware
power collapse (PC) setting failed for multiple times because
skip_pc_count is being reset when SYS_PC_PREP command is sent
to video firmware. Avoid skip_pc_count resetting while sending
SYS_PC_PREP command to make video driver raise sys_error when
power collapse setting failed.

CRs-Fixed: 2097535
Change-Id: I394e946f7017414ebc0447a38fe4b8ec7135331b
Signed-off-by: Maheshwar Ajja <majja@codeaurora.org>