dts: renesas: move ioport device of r7fa6m4af3cfb to r7fa6m4ax

Move ioport6, ioport7, ioport8 to r7fa6m4ax due to it is common
part of RA6M4
Impacted file:
- dts/arm/renesas/ra/ra6/r7fa6m4ax.dtsi
- dts/arm/renesas/ra/ra6/r7fa6m4af3cfb.dtsi

Signed-off-by: The Nguyen <the.nguyen.yf@renesas.com>