The compressed firmware support was supposed to be already
implemented, but it didn't work as expected in the end, because dracut
moved to use dracut-install binary. This patch adds the support of
XZ-compressed firmware installation to dracut-install for fixing the
missing piece.
At best the firmware files should be uncompressed in initrd, but this
patch simply copies the compressed file as-is, as a quick workaround.
BugLink: https://bugzilla.suse.com/show_bug.cgi?id=1146769
Signed-off-by: Takashi Iwai <tiwai@suse.de>