MAINTAINERS: Add entry for THUNDERX GPIO Driver.

Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

MAINTAINERS

@@ -12993,6 +12993,11 @@ M:	Yehezkel Bernat <yehezkel.bernat@intel.com>
 S:	Maintained
 F:	drivers/thunderbolt/
 
+THUNDERX GPIO DRIVER
+M:	David Daney <david.daney@cavium.com>
+S:	Maintained
+F:	drivers/gpio/gpio-thunderx.c
+
 TI AM437X VPFE DRIVER
 M:	"Lad, Prabhakar" <prabhakar.csengg@gmail.com>
 L:	linux-media@vger.kernel.org