[WATCHDOG] watchdog/iTCO_wdt: fix bug related to gcc uninit warning

gcc emits the following warning:

drivers/char/watchdog/iTCO_wdt.c: In function ‘iTCO_wdt_ioctl’:
drivers/char/watchdog/iTCO_wdt.c:429: warning: ‘time_left’ may be used uninitialized in this function

This indicates a condition near enough to a bug, to want to fix.
iTCO_wdt_get_timeleft() stores a value in 'time_left' iff
iTCO_version==(1 or 2).  This driver only supports versions
1 or 2, so this is ok.  However, since (a) the return value of
iTCO_wdt_get_timeleft() is handled anyway, (b) it fixes the warning,
and (c) it future-proofs the driver, we go ahead and add the obvious
return value.

Signed-off-by: Jeff Garzik <jeff@garzik.org>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Andrew Morton <akpm@osdl.org>