dmaengine: qcom: bam_dma: check if the runtime pm enabled

Disabling pm runtime at probe is not sufficient to get BAM working
on remotely controller instances. pm_runtime_get_sync() would return
-EACCES in such cases.
So check if runtime pm is enabled before returning error from bam functions.

Fixes: 5b4a6895

 ("dmaengine: qcom: bam_dma: disable runtime pm on remote controlled")
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>