ARM: dts: imx6qdl-sabrelite: move USDHC4 CD to pinctrl_usdhc4

This patch moves pin NANDF_D6 (CD) from pinctrl_hog to pinctrl_usdhc4.
It also explicitly sets the pad to 0x1b0b0, which is also the value
that it has before this patch if using mainline u-boot.

Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>