dma: imx-sdma: Remove spurious __init annotation on sdma_probe()

We can't annotate probe functions as __init since binding can occur at
any time, not just during kernel init.

Signed-off-by: Mark Brown <broonie@linaro.org>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>