qemu_capabilities: Track usb-host.guest-resets-all capability

qemu_capabilities: Track usb-host.guest-resets-all capability

We will need two attributes of usb-host device to set:
guest-reset and guest-resets-all. The former was introduced in
QEMU v4.0.0-rc0~56^2 and the other in v4.2.0-rc1~9^2. Hence,
track the latter only as it's only starting from that commit when
QEMU has both attributes.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>