ARM: imx1: mm: add call to mxc_device_init

mxc_device_init() is mandatory for mxc_aips and mxc_ahb bus registration, needed
as parents, at least, for gpio and dma.

Signed-off-by: Gwenhael Goavec-Merou <gwenhael.goavec-merou@armadeus.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>