fs/iso9660: drop reference to host-fakeroot

Since commit 41f0688d ("fs/iso9660:
convert to the filesystem infrastructure"), the is9660 logic uses the
common filesystem infrastructure, so the dependency on host-fakeroot is
no longer needed, and has actually become bogus since we switched to
host-pseudo.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>