kconfig: remove trailing whitespaces

There are still some trailing whitespaces under scripts/kconfig/tests/,
but they must be kept. Otherwise, "make testconfig" would break.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

scripts/kconfig/lxdialog/BIG.FAT.WARNING

@@ -1,4 +1,4 @@
 This is NOT the official version of dialog.  This version has been
 significantly modified from the original.  It is for use by the Linux
-kernel configuration script.  Please do not bother Savio Lam with 
+kernel configuration script.  Please do not bother Savio Lam with
 questions about this program.