board: colibri_imx7: fix usb start on solo

This fixes the following crash when run on a Colibri iMX7S aka solo:

Colibri iMX7 # usb start
starting USB...
Bus usb@30b10000: USB EHCI 1.00
Bus usb@30b20000:

The i.MX 7Solo has only one single USB OTG1 but no USB host port. Trying
to initialize the nonexisting port just crashes.

While at it also drop board_usb_phy_mode() which is also no longer used
in the driver model age.

Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
2 files changed