zedboard: Upgrade to Linux xilinx-v2015.1 (3.18)

Signed-off-by: Jan Viktorin <viktorin@rehivetech.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

configs/zedboard_defconfig

@@ -8,7 +8,7 @@ BR2_TARGET_GENERIC_GETTY_PORT="ttyPS0"
 BR2_LINUX_KERNEL=y
 BR2_LINUX_KERNEL_CUSTOM_GIT=y
 BR2_LINUX_KERNEL_CUSTOM_REPO_URL="git://github.com/Xilinx/linux-xlnx.git"
-BR2_LINUX_KERNEL_CUSTOM_REPO_VERSION="xilinx-v2014.1"
+BR2_LINUX_KERNEL_CUSTOM_REPO_VERSION="xilinx-v2015.1"
 BR2_LINUX_KERNEL_DEFCONFIG="xilinx_zynq"
 BR2_LINUX_KERNEL_UIMAGE_LOADADDR="0x8000"
 BR2_LINUX_KERNEL_DTS_SUPPORT=y