wl12xx: Do end-of-transactions transfers only if needed
On newer hardware revisions, there is no need to write the host's
counter at the end of a RX transaction. The same applies to writing the
number of packets at the end of a TX transaction.
It is generally a good idea to avoid unnecessary SDIO/SPI transfers.
Throughput and CPU usage are improved when avoiding these.
Send the host's RX counter and the TX packet count only if needed, based
on the hardware revision.
[Changed WL12XX_QUIRK_END_OF_TRANSACTION to use BIT(0) -- Luca]