arm64: defconfig: Enable CONFIG_SPI_IMX

Enable the CONFIG_SPI_IMX option so that i.MX8M can use the
imx spi driver by default.
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/configs/defconfig

@@ -358,6 +358,7 @@ CONFIG_SPI_ARMADA_3700=y
 CONFIG_SPI_BCM2835=m
 CONFIG_SPI_BCM2835AUX=m
 CONFIG_SPI_NXP_FLEXSPI=y
+CONFIG_SPI_IMX=m
 CONFIG_SPI_MESON_SPICC=m
 CONFIG_SPI_MESON_SPIFC=m
 CONFIG_SPI_ORION=y