MIPS: OCTEON: Get rid of CONFIG_CAVIUM_OCTEON_HW_FIX_UNALIGNED

When you turn it off, the kernel is unusable, so get rid of the option
and always allow unaligned access.

The Octeon specific memcpy intentionally does unaligned accesses and it
must not fault.

Signed-off-by: David Daney <david.daney@cavium.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5303/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>