soc/intel/{adl, mtl}: Reduce CAR usage while using FSP debug binaries

Reduces the CAR (Cache-as-RAM) variable usage while using FSP debug binaries, which can prevent the CAR from becoming too full and unable
to integrate other CAR global variables.

This change has the following downsides:

- FSP debug output into the cbmem buffer will be partial.

To test this change, you can:

Build and boot google/rex without any function impact with non-serial
and serial FSP debug image (unless what has been documented here).

Bug=b:284124701
TEST=Able to build and boot google/rex.

Change-Id: I16a1aa25fd32327d03a37381a696c86c95014ba0
Signed-off-by: Subrata Banik <subratabanik@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/76540
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Kapil Porwal <kapilporwal@google.com>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>

src/soc/intel/alderlake/Kconfig

@@ -382,7 +382,6 @@ config CBFS_SIZE
 
 config PRERAM_CBMEM_CONSOLE_SIZE
 	hex
-	default 0x16000 if CONSOLE_SERIAL
 	default 0x4000
 
 config CONSOLE_CBMEM_BUFFER_SIZE

src/soc/intel/meteorlake/Kconfig

@@ -329,7 +329,6 @@ config CBFS_SIZE
 
 config PRERAM_CBMEM_CONSOLE_SIZE
 	hex
-	default 0x16000 if BUILDING_WITH_DEBUG_FSP
 	default 0x2000
 
 config CONSOLE_CBMEM_BUFFER_SIZE