msm: vidc: Specify the min and max values for *_RATE_CONTROL_TIMESTAMP_MODE

Without specifying the min and max accepted values for V4L2_CID_MPEG_VIDC\
_VIDEO_RATE_CONTROL_TIMESTAMP_MODE, the v4l2 controls framework rejects
all values of the control when S_CTRL is called.

CRs-Fixed: 620606
Change-Id: I3a22022da40cc4ff8e3c3a4670ac2365b8e21531
Signed-off-by: Deva Ramasubramanian <dramasub@codeaurora.org>