mfd: Enable compile testing for max77620 and max77686

The OF is not a strict build-time dependency so max77620 and max77686
can be compile tested to increase build coverage.

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/Kconfig

@@ -578,7 +578,7 @@ config MFD_MAX14577
 config MFD_MAX77620
 	bool "Maxim Semiconductor MAX77620 and MAX20024 PMIC Support"
 	depends on I2C=y
-	depends on OF
+	depends on OF || COMPILE_TEST
 	select MFD_CORE
 	select REGMAP_I2C
 	select REGMAP_IRQ
@@ -593,7 +593,7 @@ config MFD_MAX77620
 config MFD_MAX77686
 	tristate "Maxim Semiconductor MAX77686/802 PMIC Support"
 	depends on I2C
-	depends on OF
+	depends on OF || COMPILE_TEST
 	select MFD_CORE
 	select REGMAP_I2C
 	select REGMAP_IRQ