ALSA: dmaengine_pcm: No need to take runtime reference twice in pcm_pointer

The runtime pointer has been taken in functional level so there is no need
to take it again under the if () case.

Fixes: 9d789dc0 ("ALSA: dmaengine_pcm: Consider DMA cache caused delay in pointer callback")
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Link: https://lore.kernel.org/r/20200227093544.27723-1-peter.ujfalusi@ti.com


Signed-off-by: Mark Brown <broonie@kernel.org>