phy: fix build breakage: add PHY_MODE_SATA

Commit 49e54187 ("ata: libahci_platform: comply to PHY framework") uses
the PHY_MODE_SATA, but that enum had not yet been added. This caused a
build failure for me, with today's linux.git.

Also, there is a potentially conflicting (mis-named) PHY_MODE_SATA, hiding
in the Marvell Berlin SATA PHY driver.

Fix the build by:

    1) Renaming Marvell's defined value to a more scoped name,
       in order to avoid any potential conflicts: PHY_BERLIN_MODE_SATA.

    2) Adding the missing enum, which was going to be added anyway as part
       of [1].

[1] https://lkml.kernel.org/r/20190108163124.6409-3-miquel.raynal@bootlin.com

Fixes: 49e54187

 ("ata: libahci_platform: comply to PHY framework")

Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Acked-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Olof Johansson <olof@lixom.net>
Cc: Grzegorz Jaszczyk <jaz@semihalf.com>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>