soc/intel/xeon_sp: Add helper functions

soc/intel/xeon_sp: Add helper functions

Provide a helper function to locate PCI devices on a given socket
by their PCI vendor and device IDs and functions to return
information about the current device, like the corresponding stack
and socket.
In addition add functions to return "location" information, like stack
and socket affiliation.
This becomes handy when locating devices and generating ACPI code.

Change-Id: I266360588548ba579f46b228c4d5b3ae6e39a029
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/80094
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Shuo Liu <shuo.liu@intel.com>
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>