ARM: zynq: Add jtag distro boot support

This patch adds new jtag distro boot command to look for bootscript
file in DDR and execute it first incase of jtag bootmode.

Signed-off-by: T Karthik Reddy <t.karthik.reddy@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/board/xilinx/zynq/board.c b/board/xilinx/zynq/board.c
index 390d948..420a5ca 100644
--- a/board/xilinx/zynq/board.c
+++ b/board/xilinx/zynq/board.c
@@ -50,7 +50,7 @@
 		env_set("modeboot", "sdboot");
 		break;
 	case ZYNQ_BM_JTAG:
-		mode = "pxe dhcp";
+		mode = "jtag pxe dhcp";
 		env_set("modeboot", "jtagboot");
 		break;
 	default: