Revert "wifi: libertas: reject short monitor TX frames"

This reverts commit 13ff543e0b2c713aedeaadadde686686e949dc78.

The 'goto free' just made things worse, causing a spinlock
to be handled incorrectly. Revert this for now.

Reported-by: Takashi Iwai <tiwai@suse.de>
Cc: stable@vger.kernel.org
Fixes: 13ff543e0b2c ("wifi: libertas: reject short monitor TX frames")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>