ASoC: stm32: sai: fix noderef.cocci warnings

sound/soc/stm/stm32_sai_sub.c:393:26-32: ERROR: application of sizeof to pointer

 sizeof when applied to a pointer typed expression gives the size of
 the pointer

Generated by: scripts/coccinelle/misc/noderef.cocci

Fixes: 8307b2af

 ("ASoC: stm32: sai: set sai as mclk clock provider")
CC: Olivier Moysan <olivier.moysan@st.com>
Signed-off-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>