deb-pkg: Install linux-firmware-image in versioned dir

That way they don't file conflict with official firmware package:
 trying to overwrite '/lib/firmware/qlogic/1040.bin', which is
               also in package firmware-qlogic 0.35
..

Reported-by: Michael Prokop <mika@debian.org>
Signed-off-by: maximilian attems <max@stro.at>
Signed-off-by: Michal Marek <mmarek@suse.cz>