MIPS: OCTEON: Use device tree to probe for flash chips.

Don't assume they are there, the device tree will tell us.

Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: Aleksey Makarov <aleksey.makarov@auriga.com>
Tested-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/9461/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>