ARM: imx: remove unused defines

None of the defines "for modules using static and dynamic DMA channels"
are used. Remove these.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Shawn Guo <shawn.guo@freescale.com>