acpi/ghes: Change the type for source_id

acpi/ghes: Change the type for source_id

As described at: ACPI 6.5 spec at:
	18.3.2. ACPI Error Source

In particular at GHES/GHESv2 table:
	Table 18.10 Generic Hardware Error Source Structure

HEST source ID is actually a 16-bit value.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <0e83ba548c1aedd1299fe387b94db78986590a34.1736945236.git.mchehab+huawei@kernel.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>