soc: renesas: rmobile-sysc: Stop using __raw_*() I/O accessors

There is no reason to keep on using the __raw_{read,write}l() I/O
accessors in Renesas ARM driver code.  Switch to using the plain
{read,write}l() I/O accessors, to have a chance that this works on
big-endian.

Suggested-by: Arnd Bergmann <arnd@kernel.org>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20201119125214.4065925-1-geert+renesas@glider.be