pinctrl: sh-pfc: Remove obsolete sh_pfc_pin_to_bias_info()

All users of sh_pfc_pin_to_bias_info() and the related data structures
have been converted to sh_pfc_pin_to_bias_reg(), so those can be
removed.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>