ARM: mach-shmobile: sh7372: make sure that fsi is peripheral of spu2

FSI act as peripheral circuits of the SPU2.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Acked-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>