feat(libfdt): upgrade libfdt source files

Update the libfdt source files to the upstream commit e37c256 [1].

[1] https://github.com/dgibson/dtc/commit/e37c256

Change-Id: I00e29b467ff6f8c094f68245232a7cedeaa14aef
Signed-off-by: Daniel Boulby <daniel.boulby@arm.com>
diff --git a/lib/libfdt/libfdt_internal.h b/lib/libfdt/libfdt_internal.h
index d4e0bd4..16bda19 100644
--- a/lib/libfdt/libfdt_internal.h
+++ b/lib/libfdt/libfdt_internal.h
@@ -46,6 +46,25 @@
 	return (void *)(uintptr_t)fdt_mem_rsv_(fdt, n);
 }
 
+/*
+ * Internal helpers to access tructural elements of the device tree
+ * blob (rather than for exaple reading integers from within property
+ * values).  We assume that we are either given a naturally aligned
+ * address for the platform or if we are not, we are on a platform
+ * where unaligned memory reads will be handled in a graceful manner.
+ * If not the external helpers fdtXX_ld() from libfdt.h can be used
+ * instead.
+ */
+static inline uint32_t fdt32_ld_(const fdt32_t *p)
+{
+	return fdt32_to_cpu(*p);
+}
+
+static inline uint64_t fdt64_ld_(const fdt64_t *p)
+{
+	return fdt64_to_cpu(*p);
+}
+
 #define FDT_SW_MAGIC		(~FDT_MAGIC)
 
 /**********************************************************************/