[ARM] pxa: create arch/arm/mach-pxa/device.c for all on-chip devices

Considering that generic.c is getting more and more bloated by device
information, moving that part out side will be much cleaner.

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