Allow provisioning to reach max oversubscription

Allow provisioning to reach max oversubscription

Currently if provisioned ratio is equal to max_over_subscription_ratio,
the capacity filter does not allow any more thin provisioning. This patch
makes a change so that thin provisioning is allowed if provisioned ratio
is equal to max_over_subscription_ratio; it will only stop provisioning
if provisioned ratio is greater than max_over_subscription_ratio.

Change-Id: Ibf13ef97472b80a1b59ffd4389a4ed2eacf67205
Partial-Bug: #1458976
(cherry picked from commit ab017d98b1bb39d218bd93970c0e561c685b7dbf)