Configurations/10-main.conf: remove MIPS bn_div_3_words.

It's being replaced with constant-time alternative.

Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7589)

(cherry picked from commit b34446cc)