qapi: Mechanically convert FOO_lookup[...] to FOO_str(...)

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <1503564371-26090-14-git-send-email-armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
diff --git a/block/nfs.c b/block/nfs.c
index bec16b7..337fcd9 100644
--- a/block/nfs.c
+++ b/block/nfs.c
@@ -772,7 +772,7 @@
 
     if (prealloc != PREALLOC_MODE_OFF) {
         error_setg(errp, "Unsupported preallocation mode '%s'",
-                   PreallocMode_lookup[prealloc]);
+                   PreallocMode_str(prealloc));
         return -ENOTSUP;
     }