sh-pfc: r8a7778: add VIN pin groups

Add VIN DATA[0:8]/CLK/HSYNC/VSYNC pin groups to R8A7778 PFC driver.
While at it, add SH_PFC_MUX8() macro for 8-bit data busses.

Signed-off-by: Vladimir Barinov <vladimir.barinov@cogentembedded.com>
[Sergei: updated the copyrights, added SH_PFC_MUX8() macro for 8-bit data bus,
made use of SH_PFC_*() macros to define the pin groups.]
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>