ARM: sa1111: register sa1111 devices with dmabounce in bus notifier

Use the bus notifier to register sa1111 devices with dmabounce, rather
than after the device has been registered, potentially racing with
driver binding.

Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>