sh-pfc: r8a7791: Fix msiof groups to follow GROUP

SH_PFC_PIN_GROUP(), pins[], mux[], defines
 clk, sync, ss1, ss2, rx, tx
But, msiof?_groups[] defines
 clk, ctrl, data

Fix msiof[012]_groups members to be consistent to PIN_GROUP.

Signed-off-by: Takashi Yoshii <takasi-y@ops.dti.ne.jp>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>