ARM: shmobile: kzm9g: tidyup FSI pinctrl

sh73a0 needs "sh_fsi2", not "sh_fsi2.0"

Tested-by: Hiep Cao Minh <cm-hiep@jinso.co.jp>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>