pinctrl: sh-pfc: Remove obsolete SH_PFC_PIN_NAMED*() macros

Now all Renesas pin control drivers have been converted to use the new
non-GPIO helper macros, SH_PFC_PIN_NAMED() and SH_PFC_PIN_NAMED_CFG()
are no longer used.  Remove them.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>