soc/intel/mtl: Override the `SOC_PHYSICAL_ADDRESS_WIDTH` as integer

This patch enforces consistent override handling for integer
`SOC_PHYSICAL_ADDRESS_WIDTH` config

Change-Id: Ib5bdfdb8c2689803c9d3c2bfd353609edae91ab3
Signed-off-by: Subrata Banik <subratabanik@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/79842
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Jakub Czapiga <czapiga@google.com>

src/soc/intel/meteorlake/Kconfig

@@ -466,6 +466,7 @@ config SOC_INTEL_METEORLAKE_SIGN_OF_LIFE
 	  and CSME update.
 
 config SOC_PHYSICAL_ADDRESS_WIDTH
+	int
 	default 42
 
 endif