MAINTAINERS: add linux-gpio mailing list

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/MAINTAINERS b/MAINTAINERS
index fd3a495..e9049a8 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3566,6 +3566,7 @@
 M:	Grant Likely <grant.likely@linaro.org>
 M:	Linus Walleij <linus.walleij@linaro.org>
 S:	Maintained
+L:	linux-gpio@vger.kernel.org
 T:	git git://git.secretlab.ca/git/linux-2.6.git
 F:	Documentation/gpio.txt
 F:	drivers/gpio/