superiotool: Update README with Git repository URL and directory location

Change-Id: I36d980cea5ca9cc67262dba809441091757e1fb5
Signed-off-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-on: http://review.coreboot.org/3019
Tested-by: build bot (Jenkins)
Reviewed-by: Marc Jones <marc.jones@se-eng.com>
diff --git a/util/superiotool/README b/util/superiotool/README
index 0a969c5..2607d8d 100644
--- a/util/superiotool/README
+++ b/util/superiotool/README
@@ -18,9 +18,9 @@
 Installation
 ------------
 
- $ svn co svn://coreboot.org/repos/trunk/util/superiotool
+ $ git clone http://review.coreboot.org/p/coreboot.git
 
- $ cd superiotool
+ $ cd util/superiotool
 
 Optional: Edit the Makefile and set 'CONFIG_PCI = no' if you don't want to
 support PCI-attached "Super I/Os" (which needs libpci-dev) such as the