arm: zynq: Add identification string to Xilinx boards

It is good to see this string to make sure that u-boot which runs on the
board is the same which should run there.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/configs/zynq_zc702_defconfig b/configs/zynq_zc702_defconfig
index 0d0efc2..1d09701 100644
--- a/configs/zynq_zc702_defconfig
+++ b/configs/zynq_zc702_defconfig
@@ -2,6 +2,7 @@
 CONFIG_SYS_CONFIG_NAME="zynq_zc70x"
 CONFIG_ARCH_ZYNQ=y
 CONFIG_SYS_TEXT_BASE=0x4000000
+CONFIG_IDENT_STRING=" Xilinx Zynq ZC702"
 CONFIG_SPL_STACK_R_ADDR=0x200000
 CONFIG_DEFAULT_DEVICE_TREE="zynq-zc702"
 CONFIG_DEBUG_UART=y