e is always set with the 4th from highest phy rate,
this assumption might be wrong if we have less than that. Fix that.

Cc: stable@kernel.org
Cc: Paul Stewart <pstew@google.com>
Reported-by: Ajay Gummalla <agummalla@google.com>
Signed-off-by: Rajkumar Manoharan <rmanohar@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
νΤ