fdt/wrappers: Introduce code to find UART DT node

The stdout-path property in the /chosen node of a DTB points to a device
node, which is used for boot console output.
On most (if not all) ARM based platforms this is the debug UART.
The ST platform code contains a function to parse this property and
chase down eventual aliases to learn the node offset of this UART node.

Introduce a slightly more generalised version of this ST platform function
in the generic fdt_wrappers code. This will be useful for other platforms
as well.

Change-Id: Ie6da47ace7833861b5e35fe8cba49835db3659a5
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
diff --git a/plat/arm/board/juno/jmptbl.i b/plat/arm/board/juno/jmptbl.i
index 213afd0..09017ac 100644
--- a/plat/arm/board/juno/jmptbl.i
+++ b/plat/arm/board/juno/jmptbl.i
@@ -25,6 +25,9 @@
 fdt     fdt_next_subnode
 fdt     fdt_parent_offset
 fdt     fdt_stringlist_search
+fdt     fdt_get_alias_namelen
+fdt     fdt_path_offset
+fdt     fdt_path_offset_namelen
 mbedtls mbedtls_asn1_get_alg
 mbedtls mbedtls_asn1_get_alg_null
 mbedtls mbedtls_asn1_get_bitstring_null