ARM: dts: sun6i: Add Merrii A31 Hummingbird support

ARM: dts: sun6i: Add Merrii A31 Hummingbird support

This adds support for the A31 Hummingbird:
http://www.merrii.com/en/pla_d.asp?id=172

The Merrii A31 Hummingbird is a development board based on the
Allwinner A31 SoC with multiple USB ports through a USB hub chip,
a uSD slot, a 10/100/1000M ethernet port, an AP6210 WiFi/BT chip,
TV-in, HDMI, VGA, audio in/out ports, and LCD/CSI headers.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
[wens@csie.org: enable usbphy, ehci0, ohci0 for on-board usb hub;
 add pcf8563 rtc node; add comments for i2c0 and mmc0 pull-ups;
 correct ethernet phy address to 0x01; drop uart2 (BT chip has
 no power) and uart3 (no device); use proper commit message]
Signed-off-by: Chen-Yu Tsai <wens@csie.org>