hwmon: (smsc47b397) Fix compiler warning

Some configurations produce the following compiler warning:

drivers/hwmon/smsc47b397.c: In function 'smsc47b397_init':
drivers/hwmon/smsc47b397.c:385: warning: 'address' may be used uninitialized in this function

While this is a false positive, it can easily be fixed by overloading the return
value from smsc47b397_find with both address and error return code (the address
is an unsigned short and thus never negative). This also reduces module size by
a few bytes (64 bytes for x86_64).

Cc: Mark M. Hoffman <mhoffman@lightlink.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Robert Coulson <robert.coulson@ericsson.com>
Acked-by: Jean Delvare <khali@linux-fr.org>