[WATCHDOG] add Nano 7240 driver

Adds support for the built-in watchdog on EPIC Nano 7240 boards from IEI.

Tested on Nano-7240RS.

Hardware documentation of the platform (including watchdog) can be found
on the IEI website: http://www.ieiworld.com

Signed-off-by: Gilles Gigan <gilles.gigan@gmail.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index e4779f7..87483cc 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -72,6 +72,7 @@
 obj-$(CONFIG_PC87413_WDT) += pc87413_wdt.o
 obj-$(CONFIG_60XX_WDT) += sbc60xxwdt.o
 obj-$(CONFIG_SBC8360_WDT) += sbc8360.o
+obj-$(CONFIG_SBC7240_WDT) += sbc7240_wdt.o
 obj-$(CONFIG_CPU5_WDT) += cpu5wdt.o
 obj-$(CONFIG_SMSC37B787_WDT) += smsc37b787_wdt.o
 obj-$(CONFIG_W83627HF_WDT) += w83627hf_wdt.o