bus: sun50i-de2: Adjust printing error message

SRAM driver often returns -EPROBE_DEFER and thus this bus driver often
prints error message, even if it probes successfully later. This is
confusing for users and they often think that something is wrong.

Use dev_err_probe() helper for printing error message. It handles
-EPROBE_DEFER automatically.

Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20211010071812.145178-1-jernej.skrabec@gmail.com