MIPS: Octeon: Delete legacy hack for broken bootloaders

Delete legacy hack for broken bootloaders. The warning has been in kernel
for several years, and if there are still users using such bootloaders,
they can fix the boot by supplying a proper DTB.

Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: David Daney <ddaney@caviumnetworks.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14201/


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