zynq_zc706: u-boot: bump to xilinx-v2017.3

[Build-tested only]
Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
Acked-by: Alistair Francis <alistair.francis@xilinx.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

configs/zynq_zc706_defconfig

@@ -20,7 +20,7 @@ BR2_TARGET_UBOOT=y
 BR2_TARGET_UBOOT_BUILD_SYSTEM_KCONFIG=y
 BR2_TARGET_UBOOT_CUSTOM_GIT=y
 BR2_TARGET_UBOOT_CUSTOM_REPO_URL="https://github.com/Xilinx/u-boot-xlnx.git"
-BR2_TARGET_UBOOT_CUSTOM_REPO_VERSION="xilinx-v2017.1"
+BR2_TARGET_UBOOT_CUSTOM_REPO_VERSION="xilinx-v2017.3"
 BR2_TARGET_UBOOT_BOARD_DEFCONFIG="zynq_zc706"
 BR2_TARGET_UBOOT_NEEDS_DTC=y
 BR2_TARGET_UBOOT_NEEDS_OPENSSL=y