sunxi: soft-i2c: Fix gpio handling to work with the driver-model

sunxi: soft-i2c: Fix gpio handling to work with the driver-model

i2c_init_board() gets called before the driver-model (gpio) code is
initialized, so move the setup of the soft-i2c pins out of i2c_init_board()
and into board_init(), at which time the driver-model setup has been done.

Also add proper error checking and properly request the gpios as that is
mandatory with the driver-model.

Signed-off-by: Hans de Goede <[email protected]>
Reviewed-by: Simon Glass <[email protected]>
Acked-by: Ian Campbell <[email protected]>