qemu: process: Improve documentation of values handled by qemuProcessHandleAcpiOstInfo

qemu: process: Improve documentation of values handled by qemuProcessHandleAcpiOstInfo

We forgot to document the specific fields for the 0x103 and 0x200
sources which are tied to device removal and device hotplug
respectively.

The value description is based on the ACPI 6.2A standard Table 6-207 and
Table 6-208. At the time of writing of this patch the standard can be
accessed e.g. at:

https://www.uefi.org/sites/default/files/resources/ACPI%206_2_A_Sept29.pdf

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>