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/fdt_strerror.c b/lib/libfdt/fdt_strerror.c
index b435693..d852b77 100644
--- a/lib/libfdt/fdt_strerror.c
+++ b/lib/libfdt/fdt_strerror.c
@@ -39,6 +39,7 @@
 	FDT_ERRTABENT(FDT_ERR_BADOVERLAY),
 	FDT_ERRTABENT(FDT_ERR_NOPHANDLES),
 	FDT_ERRTABENT(FDT_ERR_BADFLAGS),
+	FDT_ERRTABENT(FDT_ERR_ALIGNMENT),
 };
 #define FDT_ERRTABSIZE	((int)(sizeof(fdt_errtable) / sizeof(fdt_errtable[0])))