boards: nxp: mimxrt685_evk: Fix unit and first address mismatch

This fixes the following warning:

> unit address and first address in 'reg' (0x1a0000000000000000) don't
> match for /soc/peripheral@50000000/i3c@36000/wm8904@1a

Signed-off-by: Reto Schneider <reto.schneider@husqvarnagroup.com>