MIPS: BPF: Avoid unreachable code on little endian

On little endian, avoid generating the big endian version of the code
by using #else in addition to #ifdef #endif. Also fix one alignment
issue wrt delay slot.

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Reviewed-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: stable@vger.kernel.org # v4.2+
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/11097/


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