Add non-free-firmware component to non-free images

For bookworm, raspi-firmware has been moved to the non-free-firmware component.

The non-free component is currently still required for firmware-brcm80211.

Tests:

• Build a raspberry64 image for bookworm and confirm raspi-firmware and firmware-brcm80211 packages are installed.

• Build a raspberry3-b-plus image for bookworm and confirm raspi-firmware package is installed.

• Build a raspberry64 image for bullseye. There are warnings about the non-existing component, but the build is successful.

Signed-off-by: James Valleroy jvalleroy@mailbox.org