arch/x86/car.ld: Rename suffix _start/_end

This is more in line with how linker symbol for regions are defined.

Change-Id: I0bd7ae59a27909ed0fd38e6f7193816cb57e76af
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/36695
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/cpu/intel/car/p4-netburst/cache_as_ram.S

@@ -376,7 +376,7 @@ fill_cache:
 	rep	stosl
 
 	/* Setup the stack. */
-	mov	$_car_stack_end, %esp
+	mov	$_ecar_stack, %esp
 
 	/* Need to align stack to 16 bytes at call instruction. Account for
 	the pushes below. */