zynqmp: Show EL level where U-Boot runs

Add one more print to make clear which EL level U-Boot runs.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>

board/xilinx/zynqmp/zynqmp.c

@@ -17,6 +17,8 @@ DECLARE_GLOBAL_DATA_PTR;
 
 int board_init(void)
 {
+	printf("EL Level:\tEL%d\n", current_el());
+
 	return 0;
 }