msm_vidc: venc: Change default fps for Video encoder.

V4L2 framework will not pass the fps information to firmware
if new fps = current fps. This resulted as incorrect rate
control setting to firmware. This change fixes the issue.

CRs-fixed: 396793
Change-Id: I69b66c2d06330cc00857a612f1f4e1f28a2eb2ec
Signed-off-by: Ashray Kulkarni <ashrayk@codeaurora.org>