arch/x86: Refactor CAR_GLOBAL quirk for FSP1.0

These platforms return to romstage from FSP only after
already having torn CAR down. A copy of the entire CAR
region is available and discoverable via HOB.

Previously, CBMEM console detected on-the-fly that CAR
migration had happened and relocated cbmem_console_p
accoringlin with car_sync_var(). However, if the CAR_GLOBAL
pointing to another object inside CAR is a relative offset
instead, we have a more generic solution that can be used
with timestamps code as well.

Change-Id: Ica877b47e68d56189e9d998b5630019d4328a419
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/35140
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/arch/arm/include/arch/early_variables.h

@@ -18,7 +18,9 @@
 
 static inline void *car_get_var_ptr(void *var) { return var; }
 #define car_get_var(var) (var)
-#define car_sync_var(var) (var)
 #define car_set_var(var, val) do { (var) = (val); } while (0)
 
+#define car_get_ptr car_get_var
+#define car_set_ptr car_set_var
+
 #endif