qcom/sdm845: Let SHIFT6mq use the provided Wi-Fi firmware

The firmware shipped on the Android partition doesn't work with the Linux Wi-Fi driver so use the one from linux-firmware instead.

Since wlanmdsp is fetched by tqftpserv we need it in the same directory as mba.mbn. The later has a device specific path in device tree so we add a symlink for it too.

The approach is based on what postmarketOS does since several years.

/cc @amartinz