watchdog: add amlogic watchdog support

Add support for hardware watchdog timer for Amlogic SoCs.
This driver has been heavily inspired by his Linux equivalent
(meson_gxbb_wdt.c).

Reviewed-by: Jerome Brunet <jbrunet@baylibre.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>

Signed-off-by: Philippe Boos <pboos@baylibre.com>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/MAINTAINERS b/MAINTAINERS
index b85629d..7701a9d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -161,6 +161,7 @@
 F:	drivers/pinctrl/meson/
 F:	drivers/power/domain/meson-gx-pwrc-vpu.c
 F:	drivers/video/meson/
+F:	drivers/watchdog/meson_gxbb_wdt.c
 F:	include/configs/meson64.h
 F:	include/configs/meson64_android.h
 F:	doc/board/amlogic/