ARM: shmobile: r8a7778: remove pointless PLATFORM_INFO()

remove pointless PLATFORM_INFO() macro from setup-r8a7778,
and, used original platform_device_register_xxx()

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Acked-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>