Patch from Richard Purdie

With DEBUG enabled, head.S includes arch/debug-macro.S. On the PXA, this
contains references to the macro io_p2v() so hardware.h needs to be
included.
Signed-off-by: Richard Purdie <rpurdie@openedhand.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>