genimage: change upstream URL

Pengutronix is now hosting the official genimage repository and release
tarballs on Github. This patch updates the official URL from the package
description and its download website described in GENIMAGE_SITE.

Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/genimage/Config.in.host

@@ -10,4 +10,4 @@ config BR2_PACKAGE_HOST_GENIMAGE
 	  environment variables, the config file or commandline
 	  switches.
 
-	  http://www.pengutronix.de/software/genimage/
+	  https://github.com/pengutronix/genimage

package/genimage/genimage.mk

@@ -6,7 +6,7 @@
 
 GENIMAGE_VERSION = 9
 GENIMAGE_SOURCE = genimage-$(GENIMAGE_VERSION).tar.xz
-GENIMAGE_SITE = http://www.pengutronix.de/software/genimage/download
+GENIMAGE_SITE = https://github.com/pengutronix/genimage/releases/download/v$(GENIMAGE_VERSION)
 HOST_GENIMAGE_DEPENDENCIES = host-pkgconf host-libconfuse
 GENIMAGE_LICENSE = GPL-2.0
 GENIMAGE_LICENSE_FILES = COPYING