MAINTAINERS: remove a duplicate entry for gpio-mockup

I'll be getting all GPIO e-mail now, so remove my name from reviewers
of gpio-mockup.
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

MAINTAINERS

@@ -6291,7 +6291,6 @@ F:	drivers/media/rc/gpio-ir-tx.c
 
 GPIO MOCKUP DRIVER
 M:	Bamvor Jian Zhang <bamv2005@gmail.com>
-R:	Bartosz Golaszewski <brgl@bgdev.pl>
 L:	linux-gpio@vger.kernel.org
 S:	Maintained
 F:	drivers/gpio/gpio-mockup.c