[WATCHDOG] w83697hf/hg WDT driver - patch 11

This is patch 11 in the series of patches that converts
Marcus Junker's w83697hf watchdog driver to Samuel Tardieau's
w83697hf/hg watchdog driver.

This patch contains following changes:
 - Add w83697hf_select_wdt() and w83697hf_deselect_wdt()
   so that the start/stop/ping code can directly talk to
   the watchdog.

Signed-off-by: Samuel Tardieu <sam@rfc1149.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>