dma: MX3_IPU fix depends

ARCH_MX3 was removed in commit a89cf59b :
"arm/imx: merge i.MX3 and i.MX6"
thus preventing to select MX3_IPU, thus preventing IPU and display
to work on i.MX3x SOC.
i.MX SDMA support is also affected.

Signed-off-by: Eric Bénard <eric@eukrea.com>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: Vinod Koul <vinod.koul@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>