wireless:hostap_main.c warning: variable 'iface' set but not used

The patch below fixes a warning message Im seeing with gcc 4.6.0
 CC [M]  drivers/net/wireless/hostap/hostap_main.o
drivers/net/wireless/hostap/hostap_main.c: In function 'hostap_set_multicast_list_queue':
drivers/net/wireless/hostap/hostap_main.c:744:27: warning: variable 'iface' set but not used

Signed-off-by: Justin P. Mattock <justinmattock@gmail.com>

Signed-off-by: John W. Linville <linville@tuxdriver.com>