checkpatch: accept several commits

If several commit IDs are passed to the script, process them in order.
This helps check several commits in a development branch, for instance:
  ./scripts/checkpatch.sh `git rev-list master..HEAD`

Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>
Reviewed-by: Igor Opaniuk <igor.opaniuk@linaro.org>
diff --git a/scripts/checkpatch.sh b/scripts/checkpatch.sh
index 94d8c4f..3d8f1a6 100755
--- a/scripts/checkpatch.sh
+++ b/scripts/checkpatch.sh
@@ -10,7 +10,7 @@
 usage() {
   SCR=$(basename "$0")
   echo "Usage: $SCR [--working]                 Check working area"
-  echo "       $SCR <commit>                    Check specific commit"
+  echo "       $SCR <commit>...                 Check specific commit(s)"
   echo "       $SCR --diff <commit1> <commit2>  Check diff commit1...commit2"
   echo "       $SCR --cached                    Check staging area"
   echo "       $SCR --help                      This help"
@@ -35,8 +35,8 @@
 		usage
 		;;
 	*)
-		echo "Checking commit:  "
-		checkpatch "$1"
+		echo "Checking commit(s):"
+		for c in $*; do checkpatch $c; done
 		;;
 
 esac