Fix problem with not working scripts after merge BeagleBone Black platform. (openthread#119)

Author: Przemysław Fierek

script/_initrc

@@ -95,14 +95,9 @@ without()
 if [ -f /sys/firmware/devicetree/base/model ]
 then
     # Note: 'model' is a binary file with no newline
-    cat /sys/firmware/devicetree/base/model | grep -s "BeagleBone Black" > /dev/null
-    if [ $? -eq 0 ]
-    then
-        PLATFORM=beagleboneblack
-    fi
+    cat /sys/firmware/devicetree/base/model | grep -s "BeagleBone Black" && PLATFORM=beagleboneblack
 fi
 
-
 if test -z "$PLATFORM"; then
     have_or_die lsb_release
     PLATFORM=$(lsb_release -i | cut -c17- | tr '[:upper:]' '[:lower:]')