libata: disable forced PORTS_IMPL for >= AHCI 1.3

commit 566d1827 upstream.

Some early controllers incorrectly reported zero ports in PORTS_IMPL
register and the ahci driver fabricates PORTS_IMPL from the number of
ports in those cases.  This hasn't mattered but with the new nvme
controllers there are cases where zero PORTS_IMPL is valid and should
be honored.

Disable the workaround for >= AHCI 1.3.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Andy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/g/CALCETrU7yMvXEDhjAUShoHEhDwifJGapdw--BKxsP0jmjKGmRw@mail.gmail.com


Cc: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
[wt: file is drivers/ata/ahci.c in 2.6.32]
Signed-off-by: Willy Tarreau <w@1wt.eu>