tp-qemu: drop harmful nettype setting

nettype setting in host-kernel.cfg blocked macvtap related
test loop.
Signed-off-by: NXu Tian <xutian@redhat.com>

qemu/cfg/host-kernel/Host_RHEL/6.cfg

@@ -7,7 +7,6 @@
         query_cmd = "cat /sys/kernel/mm/ksm/pages_sharing"
     virtio_net:
         vhost = "vhost=on"
-        nettype = bridge
         # enable_vhostfd only works with vhost=on
         enable_vhostfd = yes
     Win2008, Win2008r2, Win7:

qemu/cfg/host-kernel/Host_RHEL/7.cfg

@@ -15,7 +15,6 @@
         cpu_model_flags += ",hv_relaxed"
     virtio_net:
         vhost = "vhost=on"
-        nettype = bridge
         # enable_vhostfd only works with vhost=on
         enable_vhostfd = yes
     monitor_cmds_check.qmp: