pinctrl: sh-pfc: r8a7794: Add VIN pin groups

Add VIN0/1 pin groups to R8A7794 PFC driver.

Sergei:  rebased, renamed, added changelog, gathered 12  VIN1 data pins into
a single pin group, added "vin1_data10" pin group, used 'union vin_data' and
VIN_DATA_PIN_GROUP() macro to describe VIN1 pins, reversed the order of  the
VIN1 pin groups, removed unneeded empty lines, fixed  VIN1 separator comment.

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