wl12xx: 1281/1283 support - Improve Tx & Rx path

Reduced bus transactions in the Tx & Rx path.

[Removed unnecessary check wl->chip.id != CHIP_ID_1283_PG20 when
checking the quirk -- Luca]

Signed-off-by: Shahar Levi <shahar_levi@ti.com>
Reviewed-by: Luciano Coelho <coelho@ti.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>