arm64: zynqmp: Print multiboot reg in decimal

It is better to print multiboot value in decimal because boot images are
also composed in decimal not in hex.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/board/xilinx/zynqmp/zynqmp.c b/board/xilinx/zynqmp/zynqmp.c
index a6cd41a..ebb7172 100644
--- a/board/xilinx/zynqmp/zynqmp.c
+++ b/board/xilinx/zynqmp/zynqmp.c
@@ -354,7 +354,7 @@
 
 	multiboot = readl(&csu_base->multi_boot);
 
-	printf("Multiboot:\t%x\n", multiboot);
+	printf("Multiboot:\t%d\n", multiboot);
 
 	return 0;
 }