MIPS: RB532: Convert to GPIO lib

This patch converts the rb532 code to use gpio library
and register its gpio chip.

Signed-off-by: Florian Fainelli <florian@openwrt.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 1e06d23..00a23a1 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -568,7 +568,7 @@
 	select SYS_SUPPORTS_LITTLE_ENDIAN
 	select SWAP_IO_SPACE
 	select BOOT_RAW
-	select GENERIC_GPIO
+	select ARCH_REQUIRE_GPIOLIB
 	help
 	  Support the Mikrotik(tm) RouterBoard 532 series,
 	  based on the IDT RC32434 SoC.