image: Do not #if guard board_fit_image_post_process() prototype

There's no point in guarding function prototypes with #ifdefs. If a
function is not defined, the linker will notice. Having the prototype
does not affect code size.

What the #if guard takes away is the ability to use IS_ENABLED:

	if (CONFIG_IS ENABLED(FIT_IMAGE_POST_PROCESS))
		board_fit_image_post_process(...)

When the prototype is guarded, the above form cannot be used. This
leads to the proliferation of #ifdefs, and unreadable code. The
opportunity cost of the #if guard outweighs any benefits. Remove it.

Since the original version of this patch, an empty definition was
added by commit f14e6eec6c7f ("image: cleanup pre-processor usage").
The empty definition can cause silent failures, when an implementation
of board_fit_image_post_process() is expected because the linker will
not catch the missing function. Thus this patch removes this empty
inline declaration.

Fixes: f14e6eec6c7f ("image: cleanup pre-processor usage")
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/include/image.h b/include/image.h
index d5a9403..138c83d 100644
--- a/include/image.h
+++ b/include/image.h
@@ -1556,8 +1556,6 @@
  */
 int board_fit_config_name_match(const char *name);
 
-#if defined(CONFIG_SPL_FIT_IMAGE_POST_PROCESS) || \
-	defined(CONFIG_FIT_IMAGE_POST_PROCESS)
 /**
  * board_fit_image_post_process() - Do any post-process on FIT binary data
  *
@@ -1572,11 +1570,6 @@
  * @return no return value (failure should be handled internally)
  */
 void board_fit_image_post_process(void **p_image, size_t *p_size);
-#else
-static inline void board_fit_image_post_process(void **p_image, size_t *p_size)
-{
-}
-#endif /* CONFIG_SPL_FIT_IMAGE_POST_PROCESS */
 
 #define FDT_ERROR	((ulong)(-1))