board: rockchip: unblock CAN bus in spl_board_init on Jaguar

board: rockchip: unblock CAN bus in spl_board_init on Jaguar

GPIO0_B7 is routed to TXI of the on-board CAN transceiver. The
line has a pull-down per SoC default.

This means the CAN transceiver transmits a dominant zero
and blocks the CAN bus until Linux boots and reconfigures the pin.

Let's switch to pull-up as soon as we can (i.e. in SPL).
This cuts down the "bus is blocked" time from 10 seconds to < 1 second.

Of course, to this needs CONFIG_SPL_BOARD_INIT, so enable it
the Jaguar defconfig.

Signed-off-by: Jakob Unterwurzacher <jakob.unterwurzacher@cherry.de>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>