mwl8k: Invert tx queues for set_hw_spec and set_edca_params

mac80211 and mwl8k FW tx queue priorities map inversely to each other.
Fix this.

Signed-off-by: Pradeep Nemavat <pnemavat@marvell.com>
Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Tested-by: Pradeep Nemavat <pnemavat@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>