ata: libata-core: Remove support for decreasing the number of ports

ata: libata-core: Remove support for decreasing the number of ports

Commit f31871951b38 ("libata: separate out ata_host_alloc() and
ata_host_register()") added ata_host_alloc(), where the API allowed
a LLD to overallocate the number of ports supplied to ata_host_alloc(),
as long as the LLD decreased host->n_ports before calling
ata_host_register().

However, this functionally has never ever been used by a single LLD.

Because of the current API design, the assignment of ap->print_id is
deferred until registration time, which is bad, because that means that
the ata_port_*() print functions cannot be used by a LLD until after
registration time, which means that a LLD is forced to use a print
function that is non-port specific, even for a port specific error.

Remove the support for decreasing the number of ports, such that it will
be possible to assign ap->print_id earlier.

Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240703184418.723066-14-cassel@kernel.org
Signed-off-by: Niklas Cassel <cassel@kernel.org>