wireless-drivers fixes for 4.15

Hopefully the last set of fixes for 4.15.

iwlwifi

* fix DMA mapping regression since v4.14

wcn36xx

* fix dynamic power save which has been broken since the driver was commited
Merge ath-current from git://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git

ath.git fixes for 4.15. Major changes:

wcn36xx

* fix dynamic power save which has been broken since the driver was commited