bootutils: update website URL

The original homepage seems to be down. Use the sourceforge intro page
instead.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/bootutils/Config.in

@@ -6,4 +6,4 @@ config BR2_PACKAGE_BOOTUTILS
 	  either by label or explicit label= on the kernel command line,
 	  mounting it, and 'switchroot'ing is automated.
 
-	  http://bootutils.pr.linuxrulz.org/
+	  http://bootutils.sourceforge.net/