spapr_vio: Pair g_malloc() with g_free(), not free()

Spotted by Coverity with preview checker ALLOC_FREE_MISMATCH enabled
and my "coverity: Model g_free() isn't necessarily free()" model patch
applied.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Gonglei <arei.gonglei@huawei.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

hw/ppc/spapr_vio.c

@@ -648,7 +648,7 @@ int spapr_populate_vdevice(VIOsPAPRBus *bus, void *fdt)
 
     ret = 0;
 out:
-    free(qdevs);
+    g_free(qdevs);
 
     return ret;
 }