qemu: Drop comma after QEMU_CAPS_LAST in queryDirtyRateRequired[]
The idea of queryDirtyRateRequired[] is that it lists QEMU
capabilities required for given domstats record
(VIR_DOMAIN_STATS_DIRTYRATE in this particular case) and
QEMU_CAPS_LAST is used as a sentinel. Therefore, there can never
be anything after it. Drop the comma to make it more obvious.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com> Reviewed-by: Ján Tomko <jtomko@redhat.com>