wil6210: avoid Tx descriptor double write
wil6210: avoid Tx descriptor double write

Non-cacheable Tx descriptor for the last fragment of
multi-fragment frame used to be written back twice.

Refactor code to always write non-cacheable descriptor
only once

Signed-off-by: Vladimir Kondratiev <c8a2a8a61f3d885706c70f0152b140a85297f68f@qca.qualcomm.com>
Signed-off-by: Kalle Valo <7081a7d99b8c74c0698a728df19e3915a995d7e1@codeaurora.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs