arch/x86: Add <arch/romstage.h>

Start with moving all postcar_frame related function
declarations here from <arch/cpu.h>.

Change-Id: I9aeef07f9009e44cc08927c85fe1862edf5c70dc
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/34911
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/drivers/amd/agesa/mtrr_fixme.c b/src/drivers/amd/agesa/mtrr_fixme.c
index fcb353c..bbb9eb0 100644
--- a/src/drivers/amd/agesa/mtrr_fixme.c
+++ b/src/drivers/amd/agesa/mtrr_fixme.c
@@ -11,7 +11,7 @@
  * GNU General Public License for more details.
  */
 
-#include <arch/cpu.h>
+#include <arch/romstage.h>
 #include <cbmem.h>
 #include <console/console.h>
 #include <commonlib/helpers.h>
diff --git a/src/drivers/amd/agesa/romstage.c b/src/drivers/amd/agesa/romstage.c
index adf6e0d..fad49c3 100644
--- a/src/drivers/amd/agesa/romstage.c
+++ b/src/drivers/amd/agesa/romstage.c
@@ -15,6 +15,7 @@
 
 #include <arch/acpi.h>
 #include <arch/cpu.h>
+#include <arch/romstage.h>
 #include <cbmem.h>
 #include <cpu/amd/car.h>
 #include <cpu/x86/bist.h>
diff --git a/src/drivers/intel/fsp1_1/car.c b/src/drivers/intel/fsp1_1/car.c
index 67fbe69..fafe838 100644
--- a/src/drivers/intel/fsp1_1/car.c
+++ b/src/drivers/intel/fsp1_1/car.c
@@ -13,6 +13,7 @@
  * GNU General Public License for more details.
  */
 
+#include <arch/romstage.h>
 #include <arch/symbols.h>
 #include <cbmem.h>
 #include <console/console.h>
diff --git a/src/drivers/intel/fsp2_0/temp_ram_exit.c b/src/drivers/intel/fsp2_0/temp_ram_exit.c
index 075e923..342fc35 100644
--- a/src/drivers/intel/fsp2_0/temp_ram_exit.c
+++ b/src/drivers/intel/fsp2_0/temp_ram_exit.c
@@ -9,7 +9,7 @@
  * (at your option) any later version.
  */
 
-#include <arch/cpu.h>
+#include <arch/romstage.h>
 #include <console/console.h>
 #include <fsp/api.h>
 #include <fsp/util.h>