SW: drop firmware-intelwimax package from GRMLBASE

SW: drop firmware-intelwimax package from GRMLBASE

This package was "silently" dropped in Debian's firmware-nonfree
versions v20220913-1 + v20221012-1 and now is no longer available in
Debian/unstable.

Quoting from -firmware-intelwimax's source package firmware-nonfree's
git (https://salsa.debian.org/kernel-team/firmware-nonfree.git):

| commit 1dced95200c7a1780feaf6e3cf11f8739f17d22a
| Author: Didier 'OdyX' Raboud <odyx@debian.org>
| Date:   Mon Aug 22 15:44:30 2022 +0200
|
|     intelwimax: Drop Intel WiMax package
|
|     From upstream's 660d61bdf9691ddefbb3e2b3dd3fc2606ecf6779:
|
|         Drop Intel WiMax firmware
|
|         The WiMax wireless wan driver stack was dropped from upstream
|         in 2021 without any people with HW and most global WiMax
|         netowrks already shut down or being actively shutdown.
|         The last stable firmware to support WiMax was 5.10 so time to
|         drop the firmware.