spi: spi-nxp-fspi: remove the unchecked return value for nxp_fspi_clk_disable_unprep

For nxp_fspi_clk_disable_unprep(), no caller check the return value,
so remove the unchecked return value.

Signed-off-by: Haibo Chen <haibo.chen@nxp.com>
Link: https://patch.msgid.link/20250428-flexspipatch-v3-4-61d5e8f591bc@nxp.com


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