libfdt: Add functions to get/add/delete memory reservemap entries

This patch adds functions to libfdt for accessing the memory
reservation map section of a device tree blob.  fdt_num_mem_rsv()
retreives the number of reservation entries in a dtb, and
fdt_get_mem_rsv() retreives a specific reservation entry.
fdt_add_mem_rsv() adds a new entry, and fdt_del_mem_rsv() removes a
specific numbered entry.

Testcases for these new functions are also included.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
diff --git a/tests/Makefile.tests b/tests/Makefile.tests
index e97e903..c84b63d 100644
--- a/tests/Makefile.tests
+++ b/tests/Makefile.tests
@@ -1,4 +1,5 @@
-LIB_TESTS_L = root_node find_property subnode_offset path_offset \
+LIB_TESTS_L = get_mem_rsv \
+	root_node find_property subnode_offset path_offset \
 	get_name getprop get_path supernode_atdepth_offset parent_offset \
 	node_offset_by_prop_value \
 	notfound \