pinctrl: Rework Kconfig dependency for BM1880 pinctrl driver

Make the BM1880 SoC pinctrl driver depend on COMPILE_TEST to get compiler
test coverage and also select this driver by default for ARCH_BITMAIN
platform.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/pinctrl/Kconfig b/drivers/pinctrl/Kconfig
index c4ac4bf..19d8af9 100644
--- a/drivers/pinctrl/Kconfig
+++ b/drivers/pinctrl/Kconfig
@@ -110,7 +110,8 @@
 
 config PINCTRL_BM1880
 	bool "Bitmain BM1880 Pinctrl driver"
-	depends on ARCH_BITMAIN
+	depends on OF && (ARCH_BITMAIN || COMPILE_TEST)
+	default ARCH_BITMAIN
 	select PINMUX
 	help
 	  Pinctrl driver for Bitmain BM1880 SoC.