iwlwifi: mvm: fix BAR seq ctrl reporting

There is a bug in FW where the sequence control may be
incorrect, and the driver overrides it with the value
of the ieee80211 header.

However, in BAR there is no sequence control in the header,
which result with arbitrary sequence.

This access to an unknown location is bad and it makes the
logs very confusing - so fix it.

Signed-off-by: Sara Sharon <sara.sharon@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>