EDMA HAL hardware.
* The EDMA HAL code assumes the nexttbtt and intval values are in TU/8
units, rather than TU. For now, just "hack" around that here, at least
until I code up something to translate it in the HAL.
* Setup some different TXQ flags for EDMA hardware.
* The EDMA HAL doesn't support setting the first rate series via
ath_hal_setuptxdesc() - instead, a call to ath_hal_set11nratescenario()
is always required. So for now, just do an 11n rate series setup
for EDMA beacon frames.
This allows my AR9380 to successfully transmit beacon frames.
However, CABQ TX and all normal data frame TX and TX completion is
still not functional and will require some more significant code churn
to make work.
There's some TX path TDMA code in if_ath_tx.c which should be migrated
out, but first I should likely try and verify/fix/repair the TDMA support
in 9.x and -HEAD.
