watchdog: correct the name of the watchdog_core inlude file

The watchdog_core include file should have been named
watchdog_core.h and not watchdog_dev.h . Correct this.

Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

diff --cc drivers/watchdog/watchdog_core.c
Simple merge

diff --cc drivers/watchdog/watchdog_core.h
Simple merge

diff --cc drivers/watchdog/watchdog_dev.c
Simple merge