qemu_driver: Resolve Coverity COPY_PASTE_ERROR

qemu_driver: Resolve Coverity COPY_PASTE_ERROR

In qemuDomainSetBlkioParameters(), Coverity points out that the calls
to qemuDomainParseBlkioDeviceStr() are slightly different and points
out there may be a cut-n-paste error.

In the first call (AFFECT_LIVE), the second parameter is "param->field";
however, for the second call (AFFECT_CONFIG), the second parameter is
"params->field".  It seems the "param->field" is correct especially since
each path as a setting of "param" to "&params[i]".  Furthermore, there
were a few more instances of using "params[i]" instead of "param->"
which I cleaned up.

Signed-off-by: John Ferlan <jferlan@redhat.com>