watchdog: Add watchdog support for W83627DHG chip

The following adds watchdog support for the Winbond W83627DHG chip.
I have tested it on a PQ7-M102XL (Intel Atom) board.

Signed-off-by: Benny Lønstrup Ammitzbøll <benny@ammitzboell-consult.dk>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>