ipq40xx: detangle ath10k-board-qca4019 from ath10k-firmware-qca4019*

ipq40xx: detangle ath10k-board-qca4019 from ath10k-firmware-qca4019*

Back in the day, the board-2.bin came with ath10k-firmware-qca4019.
This changed with
commit c3b2efaf24b5 ("linux-firmware: ath10k: add board firmware packages")
which placed the board-2.bin into a separate package: ath10k-board-qca4019.
This was great, because it addressed one of the caveat of the original
ipq-wifi package:
commit fa03d441e96e ("firmware: add custom IPQ wifi board definitions")

|  2. updating ath10k-firmware-qca4019 will also replace
|      the board-2.bin. For this cases the user needs to
|      manually reinstall the wifi-board package once the
|      ath10k-firmware-qca4019 is updated.

This could be extended further so that ipq-wifi packages
no longer use "install-override" and the various QCA4019
variants list the ath10k-board-qca4019 as a CONFLICT
package.

Signed-off-by: Christian Lamparter <chunkeey@gmail.com>