Linux -next build failure

Build with CONFIG_TIGON3=y and CONFIG_HWMON=m

drivers/built-in.o: In function `tg3_close':
tg3.c:(.text+0xe223a): undefined reference to `hwmon_device_unregister'
drivers/built-in.o: In function `tg3_hwmon_open':
tg3.c:(.text+0xe6109): undefined reference to `hwmon_device_register'