ARM: clk-imx6q: refine sata's parent

According to IMX6D/Q RM, table 18-3, sata clock's parent is ahb, not ipg.

Signed-off-by: Sébastien Szymanski <sebastien.szymanski@armadeus.com>
Reviewed-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>