ic3: off by one in mode_show()

This should be >= ARRAY_SIZE() to avoid reading one element beyond the
end of the array.

Fixes: 3a379bbc ("i3c: Add core I3C infrastructure")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>