tests: acpi: make sure FADT is fetched only once

tests: acpi: make sure FADT is fetched only once

Whole FADT is fetched as part of RSDT referenced tables in
fetch_rsdt_referenced_tables() albeit a bit later than when FADT
is partially parsed in fadt_fetch_facs_and_dsdt_ptrs().
However there is no reason for calling fetch_rsdt_referenced_tables()
so late, just move it right after we fetched RSDT and before
fadt_fetch_facs_and_dsdt_ptrs(). That way we can reuse whole FADT
fetched by fetch_rsdt_referenced_tables() and avoid duplicate
custom fields fetching in fadt_fetch_facs_and_dsdt_ptrs().

While at it rename fadt_fetch_facs_and_dsdt_ptrs() to
test_acpi_fadt_table(). The follow up patch will merge
fadt_fetch_facs_and_dsdt_ptrs() into test_acpi_rsdt_table(),
so that we would end up calling only test_acpi_FOO_table()
for consistency for tables that require special processing.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Acked-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>