Watchdog nodes must use 'watchdog' for node name. When a 'make dtbs_check'
is performed the following warning appears:
wdt@100: $nodename:0: 'wdt@100' does not match '^watchdog(@.*|-[0-9a-f])?$'
Fix this warning up properly renaming the node into 'watchdog'.
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@xxxxxxxxx>