mtd: spinand: winbond: Configure the IO mode after the dummy cycles

mtd: spinand: winbond: Configure the IO mode after the dummy cycles

When we will change the bus interface, the action that actually performs
the transition is the IO mode register write. This means after the IO
mode register write, we should use the new bus interface. But the
->configure_chip() hook itself is not responsible of making this change
official, it is the caller that must act according to the return value.

Reorganize this helper to first configure the dummy cycles before
possibly switching to another bus interface.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>