[MIPS] Add generic GPIO support

Signed-off-by: Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index c20cd90..1f2f7a9 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -778,6 +778,9 @@
 	bool
 	select ZONE_DMA
 
+config GENERIC_GPIO
+	bool
+
 #
 # Endianess selection.  Sufficiently obscure so many users don't know what to
 # answer,so we try hard to limit the available choices.  Also the use of a