watchdog: arm_smc_wdt: add watchdog support

Implement a ARM SMCCC based driver that allow to use
a secure watchdog on the platform.

Signed-off-by: Lionel Debieve <lionel.debieve@foss.st.com>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Stefan Roese <sr@denx.de>
Tested-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 668942e..a15fbd6 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -361,6 +361,14 @@
 	  Intel Tangier SoC. If you're using a board with Intel Tangier
 	  SoC, say Y here.
 
+config WDT_ARM_SMC
+	bool "ARM SMC watchdog timer support"
+	depends on WDT && ARM_SMCCC
+	imply WATCHDOG
+	help
+	  Select this to enable Arm SMC watchdog timer. This watchdog will manage
+	  a watchdog based on ARM SMCCC communication.
+
 config SPL_WDT
 	bool "Enable driver model for watchdog timer drivers in SPL"
 	depends on SPL_DM