qemu: revert patch - bandwidth tuning in session mode

qemu: revert patch - bandwidth tuning in session mode

Since there was a valid note to patch 43b67f2e about the best spot to
check for bandwidth set call while having libvirt daemon run in session
mode, this patch reverts previous changes dealing with bandwith
(also reverts adding variable @cfg in qemuDomainGetNumaParameters which
 does not have any use at the moment, but getting and unreferencing
 driver's config) in qemu_driver.c and qemu_command.c. There will be
another patch in the series which introduces the fix itself.