[ARM] Move AMBA include files to include/linux/amba/

Since the ARM AMBA bus is used on MIPS as well as ARM, we need
to make the bus available for other architectures to use.  Move
the AMBA include files from include/asm-arm/hardware/ to
include/linux/amba/

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>