package/mtd: switch to https mirror

As mentioned in the last release notes, there is an https mirror[1].
Switch to this as ftp is not as widely supported anymore.

[1] https://lists.infradead.org/pipermail/linux-mtd/2023-August/100922.html

Signed-off-by: Brandon Maier <brandon.maier@collins.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/mtd/mtd.mk

@@ -6,7 +6,7 @@
 
 MTD_VERSION = 2.1.6
 MTD_SOURCE = mtd-utils-$(MTD_VERSION).tar.bz2
-MTD_SITE = ftp://ftp.infradead.org/pub/mtd-utils
+MTD_SITE = https://infraroot.at/pub/mtd
 MTD_LICENSE = GPL-2.0
 MTD_LICENSE_FILES = COPYING
 MTD_CPE_ID_VENDOR = mtd-utils_project