msm:cpp: Validate data lenght in Set Clock command

The lenght of the data packet recived in case of
VIDIOC_MSM_CPP_SET_CLOCK command must be validated.
It have to be equal or smaller than the size of the
variable used to hold the data. If this condition
is not met stack-based buffer overflow will occur.

Change-Id: I68002e088aaca1ca740985d9e26e9161f130b499
Signed-off-by: Iliya Varadzhakov <ivarad@codeaurora.org>