spi: mtk_spim: check slave device mode in spi-mem's supports_op

Call spi_mem_default_supports_op() in supports_op to honor the
slave's supported single/dual/quad mode settings.

diff --git a/drivers/spi/mtk_spim.c b/drivers/spi/mtk_spim.c
index cd9b9d3..2b2c31b 100644
--- a/drivers/spi/mtk_spim.c
+++ b/drivers/spi/mtk_spim.c
@@ -359,6 +359,9 @@
 	struct udevice *bus = dev_get_parent(slave->dev);
 	struct mtk_spim_priv *priv = dev_get_priv(bus);
 
+	if (!spi_mem_default_supports_op(slave, op))
+		return false;
+
 	if (op->cmd.buswidth == 0 || op->cmd.buswidth > 4 ||
 	    op->addr.buswidth > 4 || op->dummy.buswidth > 4 ||
 	    op->data.buswidth > 4)