pinctrl: sh-pfc: r8a7796: Fix IPSR and MOD_SEL register pin assignment for FSO pins group

This patch fixes IPSR{12,17,18} and MOD_SEL0 pin assignment for FSO pins
group.

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.

Fixes: f9aece73 ("pinctrl: sh-pfc: Initial R8A7796 PFC support")
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>