alpha: hook up gpiolib support

Allow people to use gpiolib on Alpha if they want to, mostly for build
coverage.  The header is a stright copy of that for Microblaze, which in
turn was taken from PowerPC.

[akpm@linux-foundation.org: define GENERIC_GPIO]
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index 9808998..e3a8277 100644
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -12,6 +12,7 @@
 	select GENERIC_IRQ_PROBE
 	select AUTO_IRQ_AFFINITY if SMP
 	select GENERIC_IRQ_SHOW
+	select ARCH_WANT_OPTIONAL_GPIOLIB
 	help
 	  The Alpha is a 64-bit general-purpose processor designed and
 	  marketed by the Digital Equipment Corporation of blessed memory,
@@ -51,6 +52,9 @@
 config GENERIC_CMOS_UPDATE
         def_bool y
 
+config GENERIC_GPIO
+	def_bool y
+
 config ZONE_DMA
 	bool
 	default y