Revert "qemu: Forbid pinning vCPUs for TCG domain"

Revert "qemu: Forbid pinning vCPUs for TCG domain"

This reverts commit 8b035c84d8a7362a87a95e6114b8e7f959685ed9.

The MTTCG impl in QEMU does allow pinning vCPUs.

When the guest is running we already check if pinning is
possible in the qemuDomainPinVcpuLive method, so this
check was adding no benefit.

When the guest is not running, we cannot know whether the
subsequent launch will use MTTCG or TCG, so we must allow
the pinning request. If the guest does use TCG on the next
launch it will fail, but this is no worse than if the user
had done a virDomainDefineXML with an XML doc specifying
vCPU pinning.

Reviewed-by: John Ferlan <jferlan@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>