spec: Move virtiofsd dep from `qemu` to `qemu-system-XXX`
    
    When we split virtiofsd out from qemu-common, the intention was it
    would be installed with `qemu-system-XXX` but not
    `qemu-system-XXX-core`, similar to how device modules are treated.
    
    It was accidentally added to the `qemu` metapackage, which is rarely
    used.
    
    This fixes that mistake.
    
    https://bugzilla.redhat.com/show_bug.cgi?id=2083155
    
    Signed-off-by: Cole Robinson <crobinso@redhat.com>