Fix missing Intel AX210 firmware files, remove unused firmwares (#3556)

Fix AX210 firmware files, this time for real. In #3549 we still had only
ucode and pnvm files for AX211, AX210 was still missing the pnvm file,
because its ucode was provided through IWLWIFI_22000 without appropriate
pnvm file. Both AX210 and AX211 firmwares are now installed with
IWLWIFI_6E which includes both pnvm and ucode files.

Also some firmwares which are not used by the current kernel can be
removed, because the kernel always only loads the most recent one.

* buildroot 01188d9c38...a2c10a16a0 (2):
  > Revert "package/linux-firmware: exclude some files from compression"
  > package/linux-firmware: fix AX210 support, stick to latest supported ucode API, reorganize the split

Fixes #3477