uboot-envtools: Change download to git.

Currently, the build system uses an openwrt mirror which does not currently
work and FTP can be unreliable under several circumstances. This change
implicitly allows using all the mirrors to download.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

package/boot/uboot-envtools/Makefile

@@ -12,12 +12,13 @@ PKG_DISTNAME:=u-boot
 PKG_VERSION:=2018.03
 PKG_RELEASE:=1
 
-PKG_BUILD_DIR:=$(BUILD_DIR)/u-boot-$(PKG_VERSION)
-PKG_SOURCE:=$(PKG_DISTNAME)-$(PKG_VERSION).tar.bz2
-PKG_SOURCE_URL:=\
-	http://mirror2.openwrt.org/sources \
-	ftp://ftp.denx.de/pub/u-boot
-PKG_HASH:=7e7477534409d5368eb1371ffde6820f0f79780a1a1f676161c48442cb303dfd
+PKG_SOURCE_PROTO:=git
+PKG_SOURCE:=$(PKG_DISTNAME)-$(PKG_VERSION).tar.xz
+PKG_SOURCE_SUBDIR:=$(PKG_DISTNAME)-$(PKG_VERSION)
+PKG_BUILD_DIR:=$(BUILD_DIR)/$(PKG_DISTNAME)-$(PKG_VERSION)
+PKG_SOURCE_URL:=https://git.denx.de/u-boot.git
+PKG_SOURCE_VERSION:=f95ab1fb6e37f0601f397091bb011edf7a98b890
+PKG_MIRROR_HASH:=b50d8b6fe0d90b92c8c147457b1b4c2ed1cdb03191085cfc57fdad77c0bfffab
 
 PKG_BUILD_DEPENDS:=fstools