MLK-20116-3 mx7ulp_evk: Remove GPIO codes for USB ID

MLK-20116-3 mx7ulp_evk: Remove GPIO codes for USB ID

The iMX7ULP B0 chip has added more pins for muxing USB ID. The A3 board
follows it to exploit PTC13 for USB ID, so we don't need to use GPIO
any longer. The USB driver can recognize the USB mode from USB PHY.

After this change, old boards with design using GPIO for USB mode won't
be supported.

Signed-off-by: Ye Li <ye.li@nxp.com>
(cherry picked from commit 706b1a41b73d9604d4a590173f86fb398a908406)
(cherry picked from commit 8302b13924a1e5c1ed356de6a9ce62198160c307)