qemu: command: move qemuBuildHubDevStr caps validation to qemu_domain
Move QEMU caps validation of QEMU_CAPS_USB_HUB to a new function in
qemu_domain.c, qemuDomainDeviceDefValidateHub(). This function is
called by qemuDomainDeviceDefValidate() to validate the sound device
in domain define time.
qemuxml2xmltest.c was adjusted to add the now required caps for
domain definition.
Reviewed-by: Cole Robinson <crobinso@redhat.com> Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>