hwmon: (it87) Support for 16-bit fan reading in it8705 >= rev 0x03

The it8705 chip supports 16-bit fan tachometers in revisions at least
>= 0x03 (Version G). This patch enables 16-bit fan readings on all
revisions >= 0x03 just like the it8712, it8716, and it8718 chips.

Signed-off-by: Andrew Paprocki <andrew@ishiboo.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>