staging: wfx: drop unused raw_link_id field

raw_link_id can be retrieved by wfx_tx_get_raw_link_id(). So, it is not
necessary to keep it in struct wfx_tx_priv.

Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200401110405.80282-19-Jerome.Pouiller@silabs.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>