MIPS: OCTEON: Protect accesses to bootbus flash with octeon_bootbus_sem.

Without this, we get bus errors.

Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: Aleksey Makarov <aleksey.makarov@auriga.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/9460/


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