pinctrl: sh-pfc: r8a7792: Add MSIOF pin groups

Add MSIOF0/1 pin groups to the R8A7792 PFC driver.

Based  on the original (and large) patch by Vladimir Barinov
<vladimir.barinov@cogentembedded.com>.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>