xilinx: zynqmp: Add debug messages for boot mode

Add debug messages to see HW boot mode and also alternative boot mode in
logs directly.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/board/xilinx/zynqmp/zynqmp.c b/board/xilinx/zynqmp/zynqmp.c
index 27bb2b0..e43177e 100644
--- a/board/xilinx/zynqmp/zynqmp.c
+++ b/board/xilinx/zynqmp/zynqmp.c
@@ -518,6 +518,9 @@
 	if (ret)
 		return -EINVAL;
 
+	debug("HW boot mode: %x\n", reg & BOOT_MODES_MASK);
+	debug("ALT boot mode: %x\n", reg >> BOOT_MODE_ALT_SHIFT);
+
 	if (reg >> BOOT_MODE_ALT_SHIFT)
 		reg >>= BOOT_MODE_ALT_SHIFT;