nios2: Use IS_ENABLED instead of #ifdefs to check config symbols
nios2: Use IS_ENABLED instead of #ifdefs to check config symbols

Make the checking for div/mul/mulx instruction config symbols easier to
read by using IS_ENABLED instead of #ifdefs.

Signed-off-by: Tobias Klauser <9249c549618448e4c699e8032ba6c7f0d7fd4b7f@distanz.ch>
Acked-by: Ley Foon Tan <95f178e5e278816be0436ff61f034a97684bdd0e@altera.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs