pinctrl: sh-pfc: Use u32 to store register addresses

Currently all PFC registers lie in low 32-bit address space. Hence use
u32 instead of unsigned long to store PFC register addresses in pinctrl
tables.  All calculations of virtual addresses use a phys_addr_t
intermediate, so we know where to add an offset if the 32-bit assumption
ever becomes false.

While this doesn't impact 32-bit builds, it would save ca. 7 KiB on a
64-bit shmobile_defconfig kernel.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>