sh-pfc: r8a7778: add MMCIF pin groups

Add MMCIF CLK/CMD/DATA groups to R8A7778 PFC driver.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>