aomenc --help: correction for deltaq-mode default.

The default is 1 (DELTA_Q_OBJECTIVE) as per 'default_extra_cfg' in
av1_cx_iface.c

Change-Id: I0bb51477030d22f9c7be2c7a25a28000bdef282d
diff --git a/apps/aomenc.c b/apps/aomenc.c
index 81321f3..59246da 100644
--- a/apps/aomenc.c
+++ b/apps/aomenc.c
@@ -632,7 +632,7 @@
     "3: cyclic refresh)");
 static const arg_def_t deltaq_mode =
     ARG_DEF(NULL, "deltaq-mode", 1,
-            "Delta qindex mode (0: off (default), 1: deltaq pred efficiency, "
+            "Delta qindex mode (0: off, 1: deltaq pred efficiency (default), "
             "2: deltaq perceptual)");
 static const arg_def_t deltalf_mode = ARG_DEF(
     NULL, "delta-lf-mode", 1, "Enable delta-lf-mode (0: off (default), 1: on)");