[SUNGEM]: Fix link error with CONFIG_HOTPLUG disabled.

gem_remove_one() is called from the __devinit gem_init_one().

Therefore, gem_remove_one() mustn't be __devexit.

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: David S. Miller <davem@davemloft.net>