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.