i2c: sun8i_rsb: Initialize chips in .child_pre_probe

Chips attached to the RSB bus require an initialization command before
they can be used. (Specifically, this command programs the chip's
runtime address.) The driver does this in its .probe_chip hook, under
the assumption that .probe_chip is called during child probe. This is
not the case; .probe_chip is only called by dm_i2c_probe, which is
intended for use by board-level code, not for chips with OF nodes.

Since this initialization command must be run before a child chip can be
used, do it before probing each child.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Acked-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>