roles/ceph-rgw: Support CRUSH device class

The pools created by `ceph-rgw` (listed in `rgw_create_pools`) now support a
`ec_crush_device_class` option to specify which device class the EC pool should
use.

It default to being omitted, which means it will use OSDs from any device class
by default.

Signed-off-by: Benoît Knecht <bknecht@protonmail.ch>

roles/ceph-rgw/tasks/rgw_create_pools.yml

@@ -5,6 +5,7 @@
     cluster: "{{ cluster }}"
     k: "{{ item.value.ec_k }}"
     m: "{{ item.value.ec_m }}"
+    crush_device_class: "{{ item.value.ec_crush_device_class | default(omit) }}"
   delegate_to: "{{ groups[mon_group_name][0] }}"
   loop: "{{ rgw_create_pools | dict2items }}"
   when: