plat/stm32: Use generic fdt_get_reg_props_by_name()

The STM32 platform port parse DT nodes to find base address to
peripherals. It does this by using its own implementation, even though
this functionality is generic and actually widely useful outside of the
STM32 code.

Re-implement fdt_get_reg_props_by_name() on top of the newly introduced
fdt_get_reg_props_by_index() function, and move it to fdt_wrapper.c.
This is removes the assumption that #address-cells and #size-cells are
always one.

Change-Id: I6d584930262c732b6e0356d98aea50b2654f789d
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
diff --git a/plat/arm/board/fvp/jmptbl.i b/plat/arm/board/fvp/jmptbl.i
index 50a5ba4..c656c79 100644
--- a/plat/arm/board/fvp/jmptbl.i
+++ b/plat/arm/board/fvp/jmptbl.i
@@ -28,6 +28,7 @@
 fdt     fdt_address_cells
 fdt     fdt_size_cells
 fdt     fdt_parent_offset
+fdt     fdt_stringlist_search
 mbedtls mbedtls_asn1_get_alg
 mbedtls mbedtls_asn1_get_alg_null
 mbedtls mbedtls_asn1_get_bitstring_null
diff --git a/plat/arm/board/juno/jmptbl.i b/plat/arm/board/juno/jmptbl.i
index eb4399e..213afd0 100644
--- a/plat/arm/board/juno/jmptbl.i
+++ b/plat/arm/board/juno/jmptbl.i
@@ -24,6 +24,7 @@
 fdt     fdt_first_subnode
 fdt     fdt_next_subnode
 fdt     fdt_parent_offset
+fdt     fdt_stringlist_search
 mbedtls mbedtls_asn1_get_alg
 mbedtls mbedtls_asn1_get_alg_null
 mbedtls mbedtls_asn1_get_bitstring_null