Move the NVDIMM validation from qemuBuildMachineCommandLine()
to a new function in qemu_domain.c, qemuDomainDeviceDefValidateMemory(),
which is called by qemuDomainDeviceDefValidate(). This allows
NVDIMM validation to occur in domain define time.

It also increments memory hotplug validation, which can be seen
by the failures in the hotplug tests in qemuxml2xmltest.c that
needed to be adjusted after the move.
Reviewed-by: NCole Robinson <crobinso@redhat.com>
Signed-off-by: NDaniel Henrique Barboza <danielhb413@gmail.com>