mfd: sun6i-prcm: Allow to compile with COMPILE_TEST

Since this driver only has a dependency on ARCH_SUNXI just because it
doesn't make any sense to run it on something else, we can definitely
enable it through COMPILE_TEST as well to get some build coverage.
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/Kconfig

@@ -1246,7 +1246,7 @@ config MFD_STA2X11
 
 config MFD_SUN6I_PRCM
 	bool "Allwinner A31 PRCM controller"
-	depends on ARCH_SUNXI
+	depends on ARCH_SUNXI || COMPILE_TEST
 	select MFD_CORE
 	help
 	  Support for the PRCM (Power/Reset/Clock Management) unit available