dmaengine: imx-sdma: Drop the invocation of pm_runtime_get_sync() in sdma_load_firmware()

It makes no sense to invoke the pm_runtime_get_sync()
for a platform which doesn't support runtime PM.

Fixed commit 2da31cfd ("dmaengine: imx-sdma: Fix a hang
when run dma test in imx8mq board")
Signed-off-by: Xiaolei Wang <xiaolei.wang@windriver.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>