ata: libahci_platform: Export again ahci_platform_<en/dis>able_phys()

ata: libahci_platform: Export again ahci_platform_<en/dis>able_phys()

BugLink: https://bugs.launchpad.net/bugs/1860602
commit 84b032dbfdf1c139cd2b864e43959510646975f8 upstream.

This reverts commit 6bb86fefa086faba7b60bb452300b76a47cde1a5
("libahci_platform: Staticize ahci_platform_<en/dis>able_phys()") we are
going to need ahci_platform_{enable,disable}_phys() in a subsequent
commit for ahci_brcm.c in order to properly control the PHY
initialization order.

Also make sure the function prototypes are declared in
include/linux/ahci_platform.h as a result.

Cc: stable@vger.kernel.org
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>