omap: rx51: Add SI4713 FM transmitter

Add SI4713 FM transmitter supplies, platform data and setup to RX-51/N900.
It is connected to line output signals of TLV320AIC34 codec A part.
Driver can be either built-in or a module. It can be tuned with v4l2-ctl
from ivtv-utils. Following examples illustrate the use of it:

	v4l2-ctl -d /dev/radio0 --set-ctrl=mute=0 (power up)
	v4l2-ctl -d /dev/radio0 -f 107900 (tune 107.9 MHz)

	v4l2-ctl -d /dev/radio0 --set-ctrl=mute=1 (power down)

Signed-off-by: Jarkko Nikula <jhnikula@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>