soc/intel/tigerlake: Generate LP4x SPD files using gen_spd.go

soc/intel/tigerlake: Generate LP4x SPD files using gen_spd.go

This change uses gen_spd.go and global_lp4x_mem_parts.json.txt to
generate SPD files for currently known LP4x memory parts that can be
used with TGL-based mainboards.

Following files are added:
1. spd-*.hex: SPD files auto-generated by gen_spd.go
2. spd_manifest.generated.txt: Manifest file auto-generated by
gen_spd.go

Mainboards can use the SPD files from SoC directly when creating SPD
binary to add to CBFS.

BUG=b:147321551,b:155239397

Change-Id: Ic3935e4f6d106cbdf496fdfa28a0991e2d238fd9
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/41875
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nick Vaccaro <nvaccaro@google.com>
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>