pinctrl: sh-pfc: r8a7795: Correct header from R-Car Gen3 to R8A7795

This source file handles r8a7795 only, which is not the sole member of
the R-Car Gen3 family.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Linus Walleij <linus.walleij@linaro.org>