pinctrl: sh-pfc: pfc-r8a7790: Rename VIN pin groups

This drops superfluous "signal" word from the pin group names
and renames data_enable group to clkenb as in the h/w manual.

Signed-off-by: Valentine Barshak <valentine.barshak@cogentembedded.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>