[media] davinci_vpfe: Use module_platform_driver macro

module_platform_driver() eliminates the boilerplate and simplifies
the code.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Acked-by: Lad, Prabhakar <prabhakar.lad@ti.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>