[media] atmel-isi: add sanity check for supported formats in try/set_fmt()

After adding the format check in try_fmt()/set_fmt(), we don't need any
format check in configure_geometry(). So make configure_geometry() as
void type.

Signed-off-by: Josh Wu <josh.wu@atmel.com>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>