xeon_sp/{cpx,skx}: Add config IFD_CHIPSET 'lbg'

This is needed for ifdtool -p to detect CPX and SKX Lewisburg PCH as IFDv2.

Change-Id: I21df9f700aedf131a38a776e76722bf918e6af84
Signed-off-by: Johnny Lin <johnny_lin@wiwynn.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/55746
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/intel/xeon_sp/cpx/Kconfig

@@ -91,6 +91,10 @@ config IED_REGION_SIZE
 	hex
 	default 0x400000
 
+config IFD_CHIPSET
+	string
+	default "lbg"
+
 config SOC_INTEL_COMMON_BLOCK_P2SB
 	def_bool y
 

src/soc/intel/xeon_sp/skx/Kconfig

@@ -59,4 +59,8 @@ config IED_REGION_SIZE
 	hex
 	default 0x400000
 
+config IFD_CHIPSET
+	string
+	default "lbg"
+
 endif