sh: migor board support

This patch adds basic support for the Migo-R board.

Only simple stuff provided by the cpu specific sh7722 code is in place now,
like serial console port, timers and usb gadget. There is also partial support
for the smc91c111 ethernet controller - unfortunately some driver header file
also needs patching (not included here) to make the driver get IRQ sense
information from the platform data.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>