[media] davinci: vpif display: Add power management support

Implement power management operations - suspend and resume as part of
dev_pm_ops for VPIF display driver.

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>