gpio: mxc: Add COMPILE_TEST support for GPIO_MXC

Add COMPILE_TEST support to GPIO_MXC driver for better compile
testing coverage.
Signed-off-by: NAnson Huang <Anson.Huang@nxp.com>
Signed-off-by: NBartosz Golaszewski <bgolaszewski@baylibre.com>

drivers/gpio/Kconfig

@@ -394,7 +394,7 @@ config GPIO_MVEBU
 
 config GPIO_MXC
 	def_bool y
-	depends on ARCH_MXC
+	depends on ARCH_MXC || COMPILE_TEST
 	select GPIO_GENERIC
 	select GENERIC_IRQ_CHIP