hwmon: (w83773g) Fix fault detection and reporting

Smatch reports:

drivers/hwmon/w83773g.c:105
	get_fault() warn: shift has higher precedence than mask

Code analysis shows that the code is indeed wrong.
Fix it, and while we are at it, drop unnecessary typecast.

Fixes: 86a10c802362 ("hwmon: Add W83773G driver")
Cc: Lei YU <mine260309@gmail.com>
Reviewed-by: Lei YU <mine260309@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>