ARM: imx: new helper function imx_add_platform_device

This should be a globally available function, see

	http://thread.gmane.org/gmane.linux.kernel/998881/focus=998882

Until this hits mainline create a similar function available for imx
platforms only.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

diff --cc arch/arm/plat-mxc/devices.c
Simple merge

diff --cc arch/arm/plat-mxc/include/mach/devices-common.h
Simple merge