[media] media: add driver for Masterkit MA901 usb radio

This patch creates a new usb-radio driver, radio-ma901.c, that supports
Masterkit MA 901 USB FM radio devices. This device plugs into both the
USB and an analog audio input or headphones, so this thing only deals
with initialization and frequency setting.

Signed-off-by: Alexey Klimov <klimov.linux@gmail.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>