[PATCH] Arch provides generic iomap missing accessors

Allow architectures to provide their own implementation of the big endian MMIO
accessors and "repeat" MMIO accessors for use by the generic iomap.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
More-or-less-tested-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>