While all errors related to invalid node device appeared to be
consistent, we might as well continue the trend of using a
common macro.  For now, we don't need virCheckNodeDeviceGoto().

* src/datatypes.h (virCheckNodeDeviceReturn): New macro.
(VIR_IS_NODE_DEVICE, VIR_IS_CONNECTED_NODE_DEVICE): Drop
unused macros.
* src/libvirt.c: Use macro throughout.
(virLibNodeDeviceError): Drop unused macro.
Signed-off-by: NEric Blake <eblake@redhat.com>