dmaengine: imx-sdma: Fix a hang when run dma test in imx8mq board

imx8mq does not set the pm_runtime variable, so the sdma_init
function is added as a sw init without runtime PM, fix commit
111097595c1cd("MLK-25465-1 dmaengine: imx-sdma: move runtime
behind to transfer phase") sdma_set_channel_priority was moved
to sdma_config_channel, but memcpy dma type did not use the
sdma_config_channel function to set the priority, so add the
priority setting in sdma_alloc_chan_resources

Signed-off-by: Xiaolei Wang <xiaolei.wang@windriver.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>