disable-wifi.sh: decreased sleep duration

platform/kobo/disable-wifi.sh

@@ -7,6 +7,13 @@ killall udhcpc default.script wpa_supplicant 2>/dev/null
 wlarm_le -i eth0 down
 ifconfig eth0 down
 
-rmmod -r dhd
-sleep 1 # sleeping a bit here may avoid system getting hung
-rmmod -r sdio_wifi_pwr
+# Some sleep in between may avoid system getting hung
+# (we test if a module is actually loaded to avoid unneeded sleeps)
+if lsmod | grep -q dhd ; then
+    usleep 200000
+    rmmod -r dhd
+fi
+if lsmod | grep -q sdio_wifi_pwr ; then
+    usleep 200000
+    rmmod -r sdio_wifi_pwr
+fi