Introduce a new flag in the controller private data, which allows selectively
disabling the OC protection. Use the standard 'disable-over-current' OF prop
to set this flag. This OC protection must be disabled on EBV SoCrates rev 1.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Stefan Roese <sr@denx.de>
Cc: Dinh Nguyen <dinguyen@kernel.org>