Revert "[media] v4l2: Add a V4L2 driver for SI476X MFD"

As requested by Andrey Smirnov <andrew.smirnov@gmail.com>, revert
this patch.

This reverts commit 30bac911.

Conflicts:
	drivers/media/radio/Kconfig
	drivers/media/radio/radio-si476x.c

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>