ACPI: APEI: EINJ: Update the documentation for EINJv2 support

Add documentation based on implementation of EINJv2 as described in ACPI
6.5.A specification.

[Tony: New user interface for device id and syndrome]

Link: https://uefi.org/specs/ACPI/6.5_A/18_Platform_Error_Interfaces.html#error-injection


Co-developed-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Zaid Alali <zaidal@os.amperecomputing.com>
Link: https://patch.msgid.link/20250617193026.637510-8-zaidal@os.amperecomputing.com


Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>