MIPS: OCTEON: Select ARCH_REQUIRE_GPIOLIB

... and create asm/mach-cavium-octeon/gpio.h so that things continue
to build.

This allows us to use the existing I2C connected GPIO expanders.

Signed-off-by: David Daney <david.daney@cavium.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Cc: linux-gpio@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/5632/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index e12764c..fdaf628 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -732,6 +732,7 @@
 	select USB_ARCH_HAS_OHCI
 	select USB_ARCH_HAS_EHCI
 	select HOLES_IN_ZONE
+	select ARCH_REQUIRE_GPIOLIB
 	help
 	  This option supports all of the Octeon reference boards from Cavium
 	  Networks. It builds a kernel that dynamically determines the Octeon