soc/intel/apollolake: use platform_segment_loaded() for CAR coherency

Instead of using arch_segment_loaded() implement
platform_segment_loaded() so as not to tangle the notion of
arch and the chipset. Lastly, add a TODO to allow filtering
of the L1D to L2 flush depending on the region loaded.

Change-Id: I52e7cd2ae6e2d95f21bdd2fe1a471a10565309cb
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/14215
Reviewed-by: Furquan Shaikh <furquan@google.com>
Tested-by: build bot (Jenkins)
Reviewed-by: Andrey Petrov <andrey.petrov@intel.com>

src/soc/intel/apollolake/car.c

@@ -26,8 +26,10 @@ static void flush_l1d_to_l2(void)
 	wrmsr(MSR_POWER_MISC, msr);
 }
 
-void arch_segment_loaded(uintptr_t start, size_t size, int flags)
+void platform_segment_loaded(uintptr_t start, size_t size, int flags)
 {
+	/* TODO: filter on address to see if L1D flushing required. */
+
 	/* Flush L1D cache to L2 on final segment loaded */
 	if (flags & SEG_FINAL)
 		flush_l1d_to_l2();