[media] rcar_vin: copy flags from pdata

The platform data is a single word, so simply copy
it into the device's private data structure than
keeping a copy of the pointer.

This will make changing to device-tree binding
easier as it is one allocation instead of two.

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>