pinctrl: sh-pfc: r8a7796: Rename RTS{0,1,3,4}# pin function definitions

This patch renames the pin function macro definitions of the GPSR5 and
IPSR{0,3,5,6,12} registers value for the RTS{0,1,3,4}# pin.

This is a correction because GPSR and IPSR register specification for
R8A7796 SoC was changed in R-Car Gen3 Hardware User's Manual Rev.0.54E.

Signed-off-by: Takeshi Kihara <takeshi.kihara.df@renesas.com>
Signed-off-by: Yoshihiro Kaneko <ykaneko0929@gmail.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>