ieee80211_get_rts_cts_rate() can return NULL, so don't rely
on its members when it does return NULL.
Signed-off-by: NRajkumar Manoharan <rmanohar@qca.qualcomm.com>
Signed-off-by: NLuis R. Rodriguez <mcgrof@do-not-panic.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>