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/i945/acpi/i945.asl b/src/northbridge/intel/i945/acpi/i945.asl
index 5e7f4ec..349234b 100644
--- a/src/northbridge/intel/i945/acpi/i945.asl
+++ b/src/northbridge/intel/i945/acpi/i945.asl
@@ -37,7 +37,7 @@
 	//})
 
 	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, 0x00004000)
 		Memory32Fixed(ReadWrite, DEFAULT_DMIBAR, 0x00001000)
 		Memory32Fixed(ReadWrite, DEFAULT_EPBAR, 0x00001000)