scripts/headers_install.sh: fix error handling

- headers_install requires at least two arguments

- missed closing quote
Signed-off-by: Javier Barrio <javier.barrio.mart@gmail.com>
Cc: Michal Marek <mmarek@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/headers_install.sh

 #!/bin/sh
 
-if [ $# -lt 1 ]
+if [ $# -lt 2 ]
 then
-	echo "Usage: headers_install.sh OUTDIR SRCDIR [FILES...]
+	echo "Usage: headers_install.sh OUTDIR SRCDIR [FILES...]"
 	echo
 	echo "Prepares kernel header files for use by user space, by removing"
 	echo "all compiler.h definitions and #includes, removing any"