dm: fdtdec: Correct a sandbox build warning

Adjust the cast to avoid a warning when stdint.h is used.

Signed-off-by: Simon Glass <sjg@chromium.org>
Tested-by: Stephen Warren <swarren@nvidia.com>
diff --git a/lib/fdtdec.c b/lib/fdtdec.c
index b361a25..0cb255f 100644
--- a/lib/fdtdec.c
+++ b/lib/fdtdec.c
@@ -123,9 +123,10 @@
 
 	if (sizep) {
 		*sizep = fdtdec_get_number(prop_size, ns);
-		debug("addr=%08llx, size=%llx\n", (u64)addr, (u64)*sizep);
+		debug("addr=%08llx, size=%llx\n", (unsigned long long)addr,
+		      (unsigned long long)*sizep);
 	} else {
-		debug("addr=%08llx\n", (u64)addr);
+		debug("addr=%08llx\n", (unsigned long long)addr);
 	}
 
 	return addr;