src/*: Specify type of DIMM_SPD_SIZE once

Specify the type of the `DIMM_SPD_SIZE` Kconfig symbol once.

Change-Id: I619833dbce6d2dbe414ed9b37f43196b4b52730e
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/57257
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by:  Felix Singer <felixsinger@posteo.net>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>

src/soc/intel/xeon_sp/cpx/Kconfig

@@ -110,7 +110,6 @@ config DIMM_MAX
 
 # DDR4
 config DIMM_SPD_SIZE
-	int
 	default 512
 
 if INTEL_TXT