Begin consolidation of of_device.h

This just moves the common stuff from the arch of_device.h files to
linux/of_device.h.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Paul Mackerras <paulus@samba.org>
Acked-by: David S. Miller <davem@davemloft.net>