ARM64: zynqmp: Decrease boot delay

Synchronize it with zynq platform.
Signed-off-by: NSoren Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: NMichal Simek <michal.simek@xilinx.com>

include/configs/xilinx_zynqmp.h

@@ -168,7 +168,7 @@
 
 #define CONFIG_PREBOOT		"run bootargs"
 #define CONFIG_BOOTCOMMAND	"run $modeboot"
-#define CONFIG_BOOTDELAY	5
+#define CONFIG_BOOTDELAY	3
 
 #define CONFIG_BOARD_LATE_INIT