pinctrl: sh-pfc: r8a7795: Use generic bias register description

Move R-Car H3 ES2.0 bias support over to the generic way to describe
bias registers, which will be needed for suspend/resume support.

As the new description is more compact, this decreases kernel size by
ca. 308 bytes.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>