edge: Fix MCS range in VTY

Change the range from MCS 1-4 to MCS 1-9.

Sponsored-by: On-Waves ehf
diff --git a/src/pcu_vty.c b/src/pcu_vty.c
index ee3116f..fe3009b 100644
--- a/src/pcu_vty.c
+++ b/src/pcu_vty.c
@@ -408,7 +408,7 @@
 
 DEFUN(cfg_pcu_mcs_max,
       cfg_pcu_mcs_max_cmd,
-      "mcs max <1-4> [<1-4>]",
+      "mcs max <1-9> [<1-9>]",
       MCS_STR
       CS_MAX_STR
       "Maximum MCS value to be used\n"