iwlwifi(4) on riscv64 (intel ax200)

I thought I simply share this here, maybe it's useful to someone. I got 
an intel wifi-6 ax200 m.2 slot card working on a HiFive Unmatched board 
w/ fbsd 15.0. It seems to work fine for me, so far, but it's in no way 
thoroughly tested...

In order to build the if_iwlwifi kernel module I needed to 
disable ACPI in the module's Makefile, and patch a source file to add 
some missing ACPI related #ifdefs.

Also, some firmware files need to be built and installed via ports' 
net/wifi-firmware-iwlwifi-kmod. Those firmware files can be built on 
any platform - when building them on riscv64 themselves, a small patch 
needs to be applied to net/wifi-firmware-kmod so riscv64 isn't excluded, 
though.

Anywho, to have a seemingly working iwlwifi(4) on my riscv64 setup, the 
following steps were needed:

1) make sure src is installed
2) apply attached patch (which does the tweaks described above)
3) build/install kernel module from source:
     cd /usr/src/sys/modules/iwlwifi
     make
     make install clean
4) install firmware port:
     cd /usr/ports/net/wifi-firmware-iwlwifi-kmod
     make install clean
5) kldload wlan_ccmp wlan_amrr if_iwlwifi

As said, thought that I share this here, happy that it's working, but no 
idea or guarantee about stability and correctness.

Cheers