crush: set_choose_tries = 100 for erasure code rulesets

crush: set_choose_tries = 100 for erasure code rulesets

It is common for people to try to map 9 OSDs out of a 9 OSDs total ceph
cluster. The default tries (50) will frequently lead to bad mappings for
this use case. Changing it to 100 makes no significant CPU performance
difference, as tested manually by running crushtool on one million
mappings.

http://tracker.ceph.com/issues/10353 Fixes: #10353

Signed-off-by: Loic Dachary <ldachary@redhat.com>