Merge tag 'mt76-for-kvalo-2019-05-01' of https://github.com/nbd168/wireless

mt76 patches for 5.2

* share more code across drivers
* new driver for MT7615 chipsets
* rework DMA API
* tx/rx performance optimizations
* use NAPI for tx cleanup on mt76x02
* AP mode support for USB devices
* USB stability fixes
* tx power handling fixes for 76x2
* endian fixes