dm: core: Inline a few ofnode functions in SPL

A recent change to unify the flattree/livetree code introduced a small
size increase in SPL on some boards. For example SPL code size for
px30-core-ctouch2-px30 increased by 40 bytes.

To address this we can take advantage of the fact that some of the ofnode
functions are only called a few times in SPL, so it is worth inlining
them.

Add new Kconfig options to control this. These functions are not inlined
for U-Boot proper, since this increases code size.

Fixes: 2ebea5eaeb ("dm: core: Combine the flattree and livetree binding code")
Signed-off-by: Simon Glass <sjg@chromium.org>

drivers/core/ofnode.c

@@ -226,6 +226,7 @@ int ofnode_read_u32_array(ofnode node, const char *propname,
 	}
 }
 
+#if !CONFIG_IS_ENABLED(DM_INLINE_OFNODE)
 bool ofnode_is_enabled(ofnode node)
 {
 	if (ofnode_is_np(node)) {
@@ -255,6 +256,7 @@ ofnode ofnode_next_subnode(ofnode node)
 	return offset_to_ofnode(
 		fdt_next_subnode(gd->fdt_blob, ofnode_to_offset(node)));
 }
+#endif /* !DM_INLINE_OFNODE */
 
 ofnode ofnode_get_parent(ofnode node)
 {