qemuDomainAttachDeviceFlags: Parse device xml as inactive

qemuDomainAttachDeviceFlags: Parse device xml as inactive

In all other drivers we are doing so. Moreover, we don't want to parse
runtime information in attach (even if the attach is meant as live)
because we are generating the runtime info ourselves. We can't trust
users they supply sane values anyway.

==1140== 9 bytes in 1 blocks are definitely lost in loss record 72 of 1,151
==1140==    at 0x4A06C2B: malloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==1140==    by 0x623C758: xmlStrndup (in /usr/lib64/libxml2.so.2.9.1)
==1140==    by 0x50FD763: virXMLPropString (virxml.c:483)
==1140==    by 0x510F8B7: virDomainDeviceInfoParseXML (domain_conf.c:3685)
==1140==    by 0x511ACFD: virDomainChrDefParseXML (domain_conf.c:7535)
==1140==    by 0x5121D13: virDomainDeviceDefParse (domain_conf.c:9918)
==1140==    by 0x13AE6313: qemuDomainAttachDeviceFlags (qemu_driver.c:6926)
==1140==    by 0x13AE65FA: qemuDomainAttachDevice (qemu_driver.c:7005)
==1140==    by 0x51C77DA: virDomainAttachDevice (libvirt.c:10231)
==1140==    by 0x127FDD: remoteDispatchDomainAttachDevice (remote_dispatch.h:2404)
==1140==    by 0x127EC5: remoteDispatchDomainAttachDeviceHelper (remote_dispatch.h:2382)
==1140==    by 0x5241F81: virNetServerProgramDispatchCall (virnetserverprogram.c:437)

When doing live attach, we are passing the inactive definition anyway
since we are passing the result of virDomainDeviceDefCopy() which does
inactive copy by default.

Moreover, we are doing the same mistake in qemuhotplugtest.

Just a side note - it makes perfect sense to parse the runtime info
like alias in qemuDomainDetachDevice and qemuDomainUpdateDeviceFlags()
as in some cases the only difference to distinguish two devices can be
just their alias.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>