package/linux-firmware: prepare new firmware and new revision for iwlwifi

There is an upcoming new firmware file for a new chipset supported by
iwlwifi, as well as a new revision of the iwlwifi firmware.

The patch only prepares the iwlwifi entries so it is easier to add them.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>