ACPI: Add a context argument for table parsing handlers

In preparation for drivers reusing the core table parsing
infrastructure, arrange for handlers to take a context argument. This
allows driver table parsing to wrap ACPI table entries in
driver-specific data.

The first consumer of this infrastructure is the CEDT parsing that
happens in the cxl_acpi driver, add a conditional
(CONFIG_ACPI_TABLE_LIB=y) export of a acpi_table_parse_cedt() helper for
this case.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Len Brown <lenb@kernel.org>
Tested-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/163553710257.2509508.14310494417463866020.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>