Documentation: driver-api: Update libata error handler information

Documentation: driver-api: Update libata error handler information

Update ``->error_handler()`` section of the libata documentation file
Documentation/driver-api/libata.rst to remove the reference to the
function ata_do_eh() as that function was removed. The reference to the
function ata_bmdma_drive_eh() is also removed as that function does not
exist at all. And while at it, cleanup the description of the various
reset operations using a bullet list.

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Niklas Cassel <cassel@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20250716020315.235457-4-dlemoal@kernel.org
Signed-off-by: Niklas Cassel <cassel@kernel.org>