ASoC: fsl_sai: use local device pointer

ASoC: fsl_sai: use local device pointer

[ Upstream commit f53f50ee21d46094a8c48970e95e38a4deaa128e ]

Use a local variable to dereference the device pointer once and use the
local variable in further calls. No functional changes.

Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Acked-by: Shengjiu Wang <shengjiu.wang@gmail.com>
Link: https://lore.kernel.org/r/20220601092342.3328644-1-m.felsch@pengutronix.de
Signed-off-by: Mark Brown <broonie@kernel.org>
Stable-dep-of: 6a564338a23c ("ASoC: fsl_asrc fsl_esai fsl_sai: allow CONFIG_PM=N")
Signed-off-by: Sasha Levin <sashal@kernel.org>