Watchdog: introduce ARM SBSA watchdog driver

According to Server Base System Architecture (SBSA) specification,
the SBSA Generic Watchdog has two stage timeouts: the first signal
(WS0) is for alerting the system by interrupt, the second one (WS1) is a
real hardware reset.
More details about the hardware specification of this device:
ARM DEN0029B - Server Base System Architecture (SBSA)

This driver can operate ARM SBSA Generic Watchdog as a single stage
In the single stage mode, when the timeout is reached, your system
will be reset by WS1. The first signal (WS0) is ignored.

Signed-off-by: Zhao Qiang <qiang.zhao@nxp.com>
Signed-off-by: Biwen Li <biwen.li@nxp.com>
Reviewed-by: Stefan Roese <sr@denx.de>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index 6316c6c..4c84c4d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -689,6 +689,7 @@
 S:	Maintained
 T:	git https://gitlab.denx.de/u-boot/custodians/u-boot-fsl-qoriq.git
 F:	drivers/watchdog/sp805_wdt.c
+F:	drivers/watchdog/sbsa_gwdt.c
 
 I2C
 M:	Heiko Schocher <hs@denx.de>