ARM: imx: rename mach dir for mx21 and mx27 to mach-imx

Finally all imx code should end up there, start with mach-mx2.  While
touching all files rename some files to use a hyphen instead of an
underscore.

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