ARM: dts: imx6q-bx50v3: change pca953x GPIO default settings

Leave pca953x P06,P07 pins on b850v3 platform and P06 pin on
b450v3/b650v3 unconfigured in the kernel space since they could be
configured as DP1_RST and DP2_RST by the applications for the DP FW
update support.

Signed-off-by: Ken Lin <ken.lin@advantech.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>