Add script to restrict openwifi only use a fixed frequency:

to avoid extra tuning/scanning operation/procedure bringing ad9361 calibration and Linux channenl setting activities

user_space/set_restrict_freq.sh

@@ -0,0 +1,20 @@
+#!/bin/bash
+
+home_dir=$(pwd)
+
+if test -d "/sys/devices/platform/fpga-axi@0/fpga-axi@0:sdr"; then
+  cd /sys/devices/platform/fpga-axi@0/fpga-axi@0:sdr
+else 
+  cd /sys/devices/soc0/fpga-axi\@0/fpga-axi\@0\:sdr
+fi
+
+# set
+if [[ -n $1 ]]; then
+  echo $1 > restrict_freq_mhz
+fi
+
+# show
+cat restrict_freq_mhz
+
+cd $home_dir
+