ARM: dts: imx6q-logicpd: Use GPIO chipselect

Using the native SPI chipselect on i.MX6 is known to be problematic.

Doing it on a imx6q-sabresd causes the SPI NOR probe to fail:

[    5.388704] spi-nor spi0.0: unrecognized JEDEC id bytes: 00 00 00 00 00 00

Use the GPIO chipselect to avoid such problem.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>