mx6cuboxi: fix board detection while patching device-tree phy nodes

mx6cuboxi: fix board detection while patching device-tree phy nodes

ft_board_setup relies on the board_type() function to optimize which phy
nodes need to be enabled for Linux.
Add calls to setup and release the board-detect GPIOs.

Also fix the switch-case statement to only enable phy address 4 for
Cubox and unknown devices.

Fixes: 741ce308 ("mx6cuboxi: fixup dtb ethernet phy nodes before booting an OS")
Signed-off-by: Josua Mayer <josua@solid-run.com>