ACPI: HMAT: Drop unused dev_fmt() and redundant 'HMAT' prefix

Remove unused macro dev_pmt() and redundant 'HMAT' prefix from
pr_*() calls.

Signed-off-by: Liu Shixin <liushixin2@huawei.com>
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>