v4l: Add frameskip parameter

v4l2_qcom_frameskip is a QCOM specific parameter to be used with
VIDIO_S_PARM to indicate that the driver might take up to
maxframeinterval nanoseconds in providing the next buffer.

Driver supports this parameter if the V4L2_CAP_QCOM_FRAMESKIP capability
is set in VIDIO_G_PARM.

Change-Id: Iebbd012b9cc75395b1e165349e7e2d9d7a77160a
Signed-off-by: Deva Ramasubramanian <dramasub@codeaurora.org>
Signed-off-by: David Brown <davidb@codeaurora.org>