dmaengine: qcom: bam_dma: fix runtime PM underflow

Commit dbad41e7

 ("dmaengine: qcom: bam_dma: check if the runtime pm enabled")
caused unbalanced pm_runtime_get/put() calls when the bam is
controlled remotely. This commit reverts it and just enables pm_runtime
in all cases, the clk_* functions already just nop when the clock is NULL.

Also clean up a bit by removing unnecessary bamclk null checks.

Suggested-by: Stephan Gerhold <stephan@gerhold.net>
Fixes: dbad41e7

 ("dmaengine: qcom: bam_dma: check if the runtime pm enabled")
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>
Link: https://lore.kernel.org/r/20220629140559.118537-1-caleb.connolly@linaro.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>