pinctrl: at91-pio4: Add COMPILE_TEST support

Add COMPILE_TEST support to the AT91 PIO4 pinctrl driver for better compile
testing coverage.
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Link: https://lore.kernel.org/r/1590234326-2194-2-git-send-email-yangtiezhu@loongson.cnSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/Kconfig

@@ -82,7 +82,7 @@ config PINCTRL_AT91
 config PINCTRL_AT91PIO4
 	bool "AT91 PIO4 pinctrl driver"
 	depends on OF
-	depends on ARCH_AT91
+	depends on ARCH_AT91 || COMPILE_TEST
 	select PINMUX
 	select GENERIC_PINCONF
 	select GPIOLIB