zephyr/Kconfig: added option for enabling WDT feed

Added option for enabling feeding the watchdog while
doing the swap operation.

Signed-off-by: Andrzej Puzdrowski <andrzej.puzdrowski@nordicsemi.no>
diff --git a/boot/zephyr/Kconfig b/boot/zephyr/Kconfig
index 05c7c10..0e00758 100644
--- a/boot/zephyr/Kconfig
+++ b/boot/zephyr/Kconfig
@@ -495,6 +495,16 @@
 
 endchoice
 
+config BOOT_WATCHDOG_FEED
+	bool "Feed the watchdog while doing swap"
+	default y if SOC_FAMILY_NRF
+	imply NRFX_WDT
+	imply NRFX_WDT0
+	imply NRFX_WDT1
+	help
+	  Enables implementation of MCUBOOT_WATCHDOG_FEED() macro which is
+	  used to feed watchdog while doing time consuming operations.
+
 endmenu
 
 config MCUBOOT_DEVICE_SETTINGS