IB/cm: Destroy idr as part of the module init error flow

Clean the idr as part of the error flow since it is a resource too.

Signed-off-by: Dotan Barak <dotanb@dev.mellanox.co.il>
Reviewed-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>