package/uboot-tools: use https:// _SITE

The tarballs are also available over https, so use that instead.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
(cherry picked from commit 9a47d734bd67dc9902ce663ec86ff4e9b1539b5b)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/uboot-tools/uboot-tools.mk

@@ -6,7 +6,7 @@
 
 UBOOT_TOOLS_VERSION = 2021.07
 UBOOT_TOOLS_SOURCE = u-boot-$(UBOOT_TOOLS_VERSION).tar.bz2
-UBOOT_TOOLS_SITE = ftp://ftp.denx.de/pub/u-boot
+UBOOT_TOOLS_SITE = https://ftp.denx.de/pub/u-boot
 UBOOT_TOOLS_LICENSE = GPL-2.0+
 UBOOT_TOOLS_LICENSE_FILES = Licenses/gpl-2.0.txt
 UBOOT_TOOLS_CPE_ID_VENDOR = denx