gpio: renesas: Add R-Car Gen5 support

gpio: renesas: Add R-Car Gen5 support

Add support for the GPIO controller block in the R-Car Gen5 SoC family.
The GPIO controller has a General Input Enable Register (INEN), whose
reset state is to have all input disabled. The GPIO controller also has
updated offsets for its control registers. U-Boot uses three registers,
INDT, POSNEG, INEN, which have updated offsets, those are handled by the
driver.

Signed-off-by: Huy Bui <huy.bui.wm@renesas.com>
Signed-off-by: Hai Pham <hai.pham.ud@renesas.com>
Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
[Marek: - Access Gen5 specific registers via driver data offsets,
        - Update commit message]