mac80211: Update to version 5.2-rc7

mac80211: Update to version 5.2-rc7

This updates mac80211 to version 5.2-rc7, this contains all the changes
to the wireless subsystem up to Linux 5.2-rc7.

* The removed patches are applied upstream
* b43 now uses kmod-lib-cordic
* Update the nl80211.h file in iw to match backports version.
* Remove the two backports from kernel 4.9, they were needed for mt76,
  but that can use the version from backports now, otherwise they
  collide and cause compile errors.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>