BCM2708: Add Raspberry Pi TV HAT Device Tree Support

This is an EXAMPLE CODE of Raspberry Pi TV HAT device tree overlay.
Although this is not a part of our release code, it has been used to verify
CXD2880 device driver with TV HAT.

Add the following line to /boot/config.txt to enable TV HAT:

dtoverlay=rpi-tv

Reboot Raspberry Pi and check the existance of /proc/device-tree/soc/spi@7e204000/cxd2880@0.
If exists, the installation is successful.  you should be able to find the following three files.
/dev/dvb/adapter0/frontend0
/dev/dvb/adapter0/demux0
/dev/dvb/adapter0/dvr0

Signed-off-by: Yasunari Takiguchi <Yasunari.Takiguchi@sony.com>
Signed-off-by: Masayuki Yamamoto <Masayuki.Yamamoto@sony.com>
Signed-off-by: Hideki Nozawa <Hideki.Nozawa@sony.com>
Signed-off-by: Kota Yonezawa <Kota.Yonezawa@sony.com>
Signed-off-by: Toshihiko Matsumoto <Toshihiko.Matsumoto@sony.com>
Signed-off-by: Satoshi Watanabe <Satoshi.C.Watanabe@sony.com>