netperf: fix command to check KVM version

'rpm -qa |grep kvm' might return multiple packages

[amos@amosk logs]$ rpm -qa |grep kvm
qemu-kvm-1.6.1-3.fc20.x86_64
libvirt-daemon-kvm-1.1.3.3-2.fc20.x86_64

[amos@amosk logs]$ rpm -q qemu-kvm
qemu-kvm-1.6.1-3.fc20.x86_64
Signed-off-by: NAmos Kong <akong@redhat.com>

generic/tests/cfg/netperf.cfg

@@ -50,7 +50,7 @@
     os_type_host = linux
     shell_prompt_host =  \[root@.{0,50}][\#\$]
     #Test base env configration
-    ver_cmd = rpm -qa |grep kvm
+    ver_cmd = rpm -q qemu-kvm
     netperf_version = 2.6.0
     netperf_download_link = ftp://ftp.netperf.org/netperf/netperf-2.6.0.tar.bz2
     pkg_md5sum = 9654ffdfd4c4f2c93ce3733cd9ed9236