ACPI: watchdog: Fix gas->access_width usage

ACPI Generic Address Structure (GAS) access_width field is not in bytes
as the driver seems to expect in few places so fix this by using the
newly introduced macro ACPI_ACCESS_BYTE_WIDTH().

Fixes: b1abf6fc ("ACPI / watchdog: Fix off-by-one error at resource assignment")
Fixes: 058dfc76 ("ACPI / watchdog: Add support for WDAT hardware watchdog")
Reported-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Cc: 4.16+ <stable@vger.kernel.org> # 4.16+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>