Fixing space issues between " and ]

When we are using '[' aka. ``test`` , before the closing ']'
we need to use a space.

Otherwise the commands return with '2' so the "expression" will be a constant
false.

Change-Id: I673762e802c28335e03390b6608cf6bbee6aaba6
diff --git a/tools/build_ramdisk.sh b/tools/build_ramdisk.sh
index 3d9f76f..7372555 100755
--- a/tools/build_ramdisk.sh
+++ b/tools/build_ramdisk.sh
@@ -22,7 +22,7 @@
         umount $MNTDIR
         rmdir $MNTDIR
     fi
-    if [ -n "$DEV_FILE_TMP" -a -e "$DEV_FILE_TMP "]; then
+    if [ -n "$DEV_FILE_TMP" -a -e "$DEV_FILE_TMP" ]; then
         rm -f $DEV_FILE_TMP
     fi
     if [ -n "$IMG_FILE_TMP" -a -e "$IMG_FILE_TMP" ]; then