LF-3132: dmaengine: imx-sdma: raise up channel0 priority after resume

LF-3132: dmaengine: imx-sdma: raise up channel0 priority after resume

For some tough multi channels test, the default priority of channel0 may
not be scheduled in 500us so that channel context can't be loaded as the
below warning, hence sdma channel transfer will be failed. So raise up
channel0 to the highest one since context load is important to all
channels. Besides, enlarge 500us to 5ms for safe since many highest channel
also may run at the same time like asrc/easrc tough test(8 channel run).

"imx-sdma 30e10000.dma-controller: Timeout waiting for CH0 ready"

Signed-off-by: Robin Gong <yibin.gong@nxp.com>
Reviewed-by: Peng Zhang <peng.zhang_8@nxp.com>