dts: arm: renesas: Add Flash HP support for Renesas RA6, RA4

- Add Flash HP support for ra6-cm4, ra6-cm33, ra4-cm33 (except
r7fa4w1ad2cng)
- Add config to set the minimal size of data which can be written
for RA4E2, RA4M2, RA4M3, RA6E1, RA6E2, RA6M1, RA6M2, RA6M3, RA6M4,
RA6M5

Signed-off-by: Khoa Nguyen <khoa.nguyen.xh@renesas.com>
Signed-off-by: Phi Tran <phi.tran.jg@bp.renesas.com>