The Orion kirkwood chips have a gatable clock per SATA channel. Add
code to get and enable this clk if it exists.
Signed-off-by: NAndrew Lunn <andrew@lunn.ch>
Tested-by: NJamie Lentin <jm@lentin.co.uk>
Signed-off-by: NMike Turquette <mturquette@linaro.org>