libfdt: Don't mask fdt_get_name() returned error

Return the error code from fdt_get_name() (contained in len when the
result is NULL) instead of masking it with FDT_ERR_BADSTRUCTURE.

Fixes: fda71da26e ("libfdt: Handle failed get_name() on BEGIN_NODE")
Reported-by: Mike McTernan <mikemcternan@google.com>
Signed-off-by: Pierre-Clément Tosi <ptosi@google.com>
Message-Id: <20220729130019.804288-1-ptosi@google.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

libfdt/fdt_check.c

@@ -66,7 +66,10 @@ int fdt_check_full(const void *fdt, size_t bufsize)
 				int len;
 
 				name = fdt_get_name(fdt, offset, &len);
-				if (!name || *name || len)
+				if (!name)
+					return len;
+
+				if (*name || len)
 					return -FDT_ERR_BADSTRUCTURE;
 			}
 			break;