spi: spi-nxp-fspi: Check return value of devm_mutex_init()

devm_mutex_init() can fail. With CONFIG_DEBUG_MUTEXES=y the mutex will
be marked as unusable and trigger errors on usage.

Add the missed check.

Fixes: 4890081 ("spi: spi-nxp-fspi: remove the goto in probe")
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20250617-must_check-devm_mutex_init-v7-1-d9e449f4d224@weissschuh.net

Author: t-8ch

drivers/spi/spi-nxp-fspi.c

@@ -1273,7 +1273,9 @@ static int nxp_fspi_probe(struct platform_device *pdev)
 	if (ret)
 		return dev_err_probe(dev, ret, "Failed to request irq\n");
 
-	devm_mutex_init(dev, &f->lock);
+	ret = devm_mutex_init(dev, &f->lock);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to initialize lock\n");
 
 	ctlr->bus_num = -1;
 	ctlr->num_chipselect = NXP_FSPI_MAX_CHIPSELECT;