ata: libata-sata: Use BIT() macro to convert tag to bit field

The BIT() macro is commonly used in the kernel.
Make use of it when converting a tag, fetched from the Successful NCQ
Commands log or the NCQ Command Error log, to a bit field.
This makes the code easier to read.

Suggested-by: Igor Pylypiv <ipylypiv@google.com>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Igor Pylypiv <ipylypiv@google.com>
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>