ARM: shmobile: BOCK-W: add Ether support

Register Ether device from bockw_init(), passing the platform data to it, adding
only the RMII pin group to bockw_pinctrl_map[].  Although the LINK signal exists
on the board, it's connected to the link/activity LED  output of the PHY, thus
the link disappears and reappears after each packet. We'd be better off ignoring
such signal and getting the link state from the PHY indirectly.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
[horms+renesas@verge.net.au: manually applied]
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>