soc/intel/alderlake: Increase cbmem buffer size to 256KB

Current size of the cbmem buffer (128KB) is insufficient to contain the
complete debug log causing the cbmem console buffer to wrap.

This patch increases cbmem buffer size to 256KB so that the complete
debug log can be stored in it.

TEST=Make sure that logs from all the boot stages can be seen using
'cbmem -c'.

Change-Id: I2099386dd87a010c3a5937bd896620270f587b1c
Signed-off-by: Tarun Tuli <taruntuli@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/71288
Reviewed-by: Subrata Banik <subratabanik@google.com>
Reviewed-by: Kapil Porwal <kapilporwal@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/intel/alderlake/Kconfig

@@ -383,6 +383,10 @@ config PRERAM_CBMEM_CONSOLE_SIZE
 	hex
 	default 0x2000
 
+config CONSOLE_CBMEM_BUFFER_SIZE
+	hex
+	default 0x40000
+
 config FSP_TYPE_IOT
 	bool
 	default n