iwlegacy: add missing null check

lq_sta has other null checks in this function.
assuming they are correct, this additional null check
should be added too.

Incorporating suggestion from Gustavo Padovan.

Signed-off-by: Greg Dietsche <Gregory.Dietsche@cuw.edu>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
1 file changed