gpio: rcar: GPIO_RCAR doesn't relate to ARM

8cd14702("gpio: rcar: Add r8a7795 (R-Car H3) support") added
GPIO support for r8a7795. r8a7795 based on CONFIG_ARM64.
OTOH, GPIO_RCAR driver can be compiled fine on non-ARM.
This patch removed ARM dependency for it.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>