ahci: add PCI ID for Marvell 88SE91A0 SATA Controller

Add support for Marvell Technology Group Ltd. 88SE91A0 SATA 6Gb/s
Controller by adding its PCI ID.

Signed-off-by: Andreas Schrägle <ajs124.ajs124@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org