staging: wfx: remove unused definitions from the hif API

staging: wfx: remove unused definitions from the hif API

Until now, hif API was directly imported from firmware sources.
However, it does not make sense to keep ton of unused structures in
the driver. Moreover, the hif API is now stable enough to be keep in
sync by importing delta from firmware.

So, drop unused definitions from the hif API.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200406111756.154086-5-Jerome.Pouiller@silabs.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>