pinctrl: sh-pfc: r8a7796: Fix MOD_SEL register pin assignment for TCLK{1,2}_{A,B} pins group

This patch fixes to set MOD_SEL2 bit19 when using TCLK2_A pin function is
selected for IPSR16 bit[23:20] or using TCLK2_B pin function is selected
for IPSR17 bit[27:24].

This is a correction to the incorrect implementation of MOD_SEL register
pin assignment for R8A7796 SoC specification of R-Car Gen3 Hardware
User's Manual Rev.0.51E or later.

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>