ath10k-firmware: WCN3990: Add board file for Oneplus 6/6T

[Dylan Van Assche <me@xxxxxxxxxxxxxxxxx>]

Hello Kalle,

I would like to include the board file for the Oneplus 6/6T smartphone.
This smartphone is manufactured by Oneplus and uses the Snapdragon 
SDM845 SoC.
At postmarketOS, we run the mainline kernel on this phone so shipping 
this board file
from upstream would be a great addition. Below, the questions from the wiki:

* description for what hardware this is:

Smartphone with a SDM845 chip and a WCN3990 Bluetooth/WiFi chip.
The WCN3990 chip is connected to 2 QM488xx radios, one is used
for 2.4Ghz and the other one for 5Ghz radio.

* origin of the board file (did you create it yourself or where you
  downloaded)

Extracted from the stock firmware.

* ids to be used with the board file (ATH10K_BD_IE_BOARD_NAME in ath10k)

- WCN3990 hw1.0
  + bus=snoc,qmi-board-id=ff,qmi-chip-id=30214,variant=oneplus_sdm845
    sha256sum: 
a46790bc201026e8f38a19f3acd749640b54b73d14e09287659a647b9cc3ee8e
    md5sum: f744a3402e260d7fd330cbc964972a5c

* attach the actual board file (board.bin)

The name of the files are equal to the id string in the board-2.bin 
(minus the ".bin")

Kind regards,
Dylan Van Assche

Attachment: bus=snoc,qmi-board-id=ff,qmi-chip-id=30214,variant=oneplus_sdm845.bin
Description: Binary data