can: rcar: drop unneeded ARM dependency

The dependency on ARM predates the dependency on ARCH_RENESAS. The
latter was introduced for Renesas arm64 SoCs first, and later extended
to cover Renesas ARM SoCs, too.

Link: https://lore.kernel.org/all/362d9ced19f3524ee8917df5681b3880c13cac85.1630416373.git.geert+renesas@glider.be


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>