MAINTAINERS: add Andy Shevchenko as reviewer for the GPIO subsystem

Andy has been a de-facto reviewer for all things GPIO for a long time so
let's make it official.

Signed-off-by: Bartosz Golaszewski <[email protected]>
Acked-by: Andy Shevchenko <[email protected]>
Reviewed-by: Linus Walleij <[email protected]>

Author: Bartosz Golaszewski

MAINTAINERS

@@ -8791,6 +8791,7 @@ F:	include/linux/gpio/regmap.h
 GPIO SUBSYSTEM
 M:	Linus Walleij <[email protected]>
 M:	Bartosz Golaszewski <[email protected]>
+R:	Andy Shevchenko <[email protected]>
 L:	[email protected]
 S:	Maintained
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux.git