[media] davinci: vpif: Add suspend/resume callbacks to vpif driver

add clock enable and disable in probe and remove functions.
Probe will succeed only if the device clock is provided instead of
assuming that the clock is always enabled. VPIF clock has to be
dealt with during suspend and resume. Implement power management
callbacks to VPIF driver to disable/enable clock on suspend/resume
respectively.

Signed-off-by: Manjunath Hadli <manjunath.hadli@ti.com>
Signed-off-by: Lad, Prabhakar <prabhakar.lad@ti.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>