i3c: convert to use i2c_new_client_device()

Move away from the deprecated API.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://lore.kernel.org/linux-i3c/20200326211002.13241-2-wsa+renesas@sang-engineering.com