intel: Define `RCBA_LENGTH` in Kconfig and use it

Change-Id: Ief81d49f04c1743b2a37633c4a35da9d6ddb0974
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/50039
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/northbridge/intel/ironlake/acpi/ironlake.asl b/src/northbridge/intel/ironlake/acpi/ironlake.asl
index c43b17b..31af469 100644
--- a/src/northbridge/intel/ironlake/acpi/ironlake.asl
+++ b/src/northbridge/intel/ironlake/acpi/ironlake.asl
@@ -10,7 +10,7 @@
 	Name (_UID, 1)
 
 	Name (PDRS, ResourceTemplate() {
-		Memory32Fixed(ReadWrite, CONFIG_FIXED_RCBA_MMIO_BASE, 0x00004000)
+		Memory32Fixed(ReadWrite, CONFIG_FIXED_RCBA_MMIO_BASE, CONFIG_RCBA_LENGTH)
 		Memory32Fixed(ReadWrite, DEFAULT_MCHBAR,   0x00008000)
 		Memory32Fixed(ReadWrite, DEFAULT_DMIBAR,   0x00001000)
 		Memory32Fixed(ReadWrite, DEFAULT_EPBAR,    0x00001000)