gpio: Add Linus Walleij as gpio co-maintainer

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/MAINTAINERS b/MAINTAINERS
index b9db108..5dc8f8d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2920,6 +2920,7 @@
 
 GPIO SUBSYSTEM
 M:	Grant Likely <grant.likely@secretlab.ca>
+M:	Linus Walleij <linus.walleij@stericsson.com>
 S:	Maintained
 T:	git git://git.secretlab.ca/git/linux-2.6.git
 F:	Documentation/gpio.txt