ARM: mxc: imx-dma on imx25 has no other TO version but TO1

The imx25 sdma script only gets TO1 version, so there is no need
to encode "to1" in the variable name.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>