ipq40xx: cut ath10k board file for mikrotik subtarget

ipq40xx: cut ath10k board file for mikrotik subtarget

Avoid shipping ath10k board file in Mikrotik initram images

Most will only ever need to use these initram images once—to initially
load OpenWrt, but fix these images for more consistent Wi-Fi performance
between the initram and installed squashfs images.

OpenWrt BUILDBOT config ignores -cut packages in the initram images build.
This results in BUILDBOT initram images including the linux-firmware
qca4019 board-2.bin, and (initram image booted) Mikrotik devices loading
a generic BDF, rather than the intended BDF data loaded
from NOR as an api 1 board_file.

buildbot snapshot booted as initram image:
cat /etc/openwrt_version
r19679-810eac8c7f
dmesg | grep ath10k | grep -E board\|BDF
[    9.794556] ath10k_ahb a000000.wifi: Loading BDF type 0
[    9.807192] ath10k_ahb a000000.wifi: board_file api 2 bmi_id 0:16
crc32 11892f9b
[   12.457105] ath10k_ahb a800000.wifi: Loading BDF type 0
[   12.464945] ath10k_ahb a800000.wifi: board_file api 2 bmi_id 0:17
crc32 11892f9b

CC: Robert Marko <robimarko@gmail.com>
Fixes: 5eee67a72fed ("ipq40xx: mikrotik: dont include ath10k-board-qca4019 by default")
Signed-off-by: John Thomson <git@johnthomson.fastmail.com.au>
Reviewed-by: Robert Marko <robimarko@gmail.com>