edksetup.sh: Use $SCRIPTNAME consistently instead of 'edksetup.sh'

Signed-off-by: Rebecca Cran <rebecca@bsdio.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
Message-Id: <20190716165538.57960-2-rebecca@bsdio.com>

edksetup.sh

@@ -49,11 +49,11 @@ function SetWorkspace()
     return 0
   fi
 
-  if [ ! ${BASH_SOURCE[0]} -ef ./edksetup.sh ] && [ -z "$PACKAGES_PATH" ]
+  if [ ! ${BASH_SOURCE[0]} -ef ./$SCRIPTNAME ] && [ -z "$PACKAGES_PATH" ]
   then
     echo Run this script from the base of your tree.  For example:
     echo "  cd /Path/To/Edk/Root"
-    echo "  . edksetup.sh"
+    echo "  . $SCRIPTNAME"
     return 1
   fi