lib/prog_loading: introduce prog_segment_loaded()

In order to not muddle arch vs chipset implementations provide
a generic prog_segment_loaded() which calls platform_segment_loaded()
and arch_segment_loaded() in that order. This allows the arch variants
to live in src/arch while the chipset/platform code can implement
their own.

Change-Id: I17b6497219ec904d92bd286f18c9ec96b2b7af25
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/14214
Reviewed-by: Furquan Shaikh <furquan@google.com>
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Andrey Petrov <andrey.petrov@intel.com>

src/arch/x86/postcar_loader.c

@@ -115,7 +115,7 @@ void run_postcar_phase(struct postcar_frame *pcf)
 	 * Signal to rest of system that another update was made to the
 	 * postcar program prior to running it.
 	 */
-	arch_segment_loaded((uintptr_t)rsl.params, sizeof(uintptr_t),
+	prog_segment_loaded((uintptr_t)rsl.params, sizeof(uintptr_t),
 		SEG_FINAL);
 
 	prog_run(&prog);