Currently not all of the Port-specific capabilities listed in the
PORT_CMD-enumeration. Let's extend that set with the Cold Presence
Detection and Mechanical Presence Switch attached to the Port flags [1] so
to closeup the set of the platform-specific port-capabilities flags.  Note
these flags are supposed to be set by the platform firmware if there is
one. Alternatively as we are about to do they can be set by means of the
OF properties.

While at it replace PORT_IRQ_DEV_ILCK with PORT_IRQ_DMPS and fix the
comment there. In accordance with [2] that IRQ flag is supposed to
indicate the state of the signal coming from the Mechanical Presence
Switch.

[1] Serial ATA AHCI 1.3.1 Specification, p.27
[2] Serial ATA AHCI 1.3.1 Specification, p.24, p.88
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>