[media] media: mx2_camera: remove dead code in mx2_camera_add_device

[media] media: mx2_camera: remove dead code in mx2_camera_add_device

This is a piece of code becoming dead since commit 650d489 ([media]
V4L: mx2_camera: remove unsupported i.MX27 DMA mode, make EMMA
mandatory).  It should have been removed together with the commit.
Remove it now.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Acked-by: Javier Martin <javier.martin@vista-silicon.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>