qemu_driver: Fix order of arguments in qemuDomainGetStatsCpuProc()

qemu_driver: Fix order of arguments in qemuDomainGetStatsCpuProc()

Just before pushing my earlier commit I've switch order of two
arguments of virProcessGetStatInfo() (as suggested in review).
However, I forgot to swap the arguments in
qemuDomainGetStatsCpuProc() which leads to userTime and sysTime
being swapped.

Fixes: 044b8744d65f8571038f85685b3c4b241162977b
Reported-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>