pinctrl: sh-pfc: r8a7791: Fix SCIF2 pinmux data

PINMUX_IPSR_MSEL() macro invocation for the TX2 signal has apparently wrong
1st argument -- most probably a result of cut&paste programming...

Fixes: 50884519 ("pinctrl: sh-pfc: r8a7791 PFC support")
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>