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>