MIPS16e2: Provide feature overrides for non-MIPS16 systems

Hardcode the absence of the MIPS16e2 ASE for all the systems that do so
for the MIPS16 ASE already, providing for code to be optimized away.

Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
Reviewed-by: James Hogan <james.hogan@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16097/


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