Revert "qemu: emit error when trying to update blkiotune group_name in qemuDomainChangeDiskLive"

https://bugzilla.redhat.com/show_bug.cgi?id=1601677

This reverts commit 047cfb05
Using numeric comparison on strings means we reject every update
that does include the group name, even if it's unchanged.
Signed-off-by: NJán Tomko <jtomko@redhat.com>
Reviewed-by: NLaine Stump <laine@laine.org>

src/qemu/qemu_domain.c

@@ -9385,9 +9385,6 @@ qemuDomainDiskChangeSupported(virDomainDiskDefPtr disk,
     CHECK_EQ(blkdeviotune.size_iops_sec,
              "blkdeviotune size_iops_sec",
              true);
-    CHECK_EQ(blkdeviotune.group_name,
-             "blkdeviotune group_name",
-             true);
 
     if (disk->serial && STRNEQ_NULLABLE(disk->serial, orig_disk->serial)) {
         virReportError(VIR_ERR_OPERATION_UNSUPPORTED,