watchdog: add sl28cpld watchdog driver

The watchdog timer is part of the sl28cpld management controller. The
watchdog timer usually supervises the bootloader boot-up and if it bites
the failsafe bootloader will be activated. Apart from that it supports
the usual board level reset and one SMARC speciality: driving the
WDT_TIMEOUT# signal.

Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index cabac29..f90f0ca 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -266,6 +266,13 @@
 	   In the single stage mode, when the timeout is reached, your system
 	   will be reset by WS1. The first signal (WS0) is ignored.
 
+config WDT_SL28CPLD
+	bool "sl28cpld watchdog timer support"
+	depends on WDT && SL28CPLD
+	help
+	  Enable support for the watchdog timer in the Kontron sl28cpld
+	  management controller.
+
 config WDT_SP805
 	bool "SP805 watchdog timer support"
 	depends on WDT