watchdog: it87_wdt: add IT8613 ID

This patch adds watchdog support for the ITE IT8613 watchdog.
IT8613 watchdog works in the same way as the other watchdogs supported
by it87_wdt.

Before this patch, IT8613 watchdog is not supported. After a modprobe,
dmesg reports:
  it87_wdt: Unknown Chip found, Chip 8613 Revision 000c
With this patch, modprobe it87_wdt recognizes the watchdog as the dmesg
output shows:
  it87_wdt: Chip IT8613 revision 12 initialized. timeout=60 sec (nowayout=0 testmode=0)

Watchdog tests on a LES v4 have been successful, the watchdog works as
expected with this patch [1].

[1] https://www.thomas-krenn.com/en/wiki/Watchdog#LES_v4

Signed-off-by: Werner Fischer <devlists@wefi.net>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/3bc0a1c2d768b23a0cd6e9f5fa0c0b5577427668.camel@wefi.net
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>