[SCSI] fusion: use ARRAY_SIZE

ARRAY_SIZE is more concise to use when the size of an array is divided by
the size of its type or the size of its first element.

Signed-off-by: Julia Lawall <julia@diku.dk>
Acked-by: "Prakash, Sathya" <Sathya.Prakash@lsi.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>