MAINTAINERS: merge at91 pinctrl entries

In order to be aware of all changes related to at91 pinctrl drivers,
merge the two entries. Make use of the opportunity to replace Atmel by
Microchip.

Signed-off-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
1 file changed