We must clear this IMX6Q_GPR13_SATA_MPLL_CLK_EN bit on i.MX6Q, otherwise
Linux will fail to find the attached drive on some boards.

This entire fix was:
Reported-by: NEric Nelson <eric.nelson@boundarydevices.com>
Signed-off-by: NMarek Vasut <marex@denx.de>
Reviewed-by: NShawn Guo <shawn.guo@linaro.org>
Cc: Richard Zhu <r65037@freescale.com>
Cc: Linux-IDE <linux-ide@vger.kernel.org>
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org