Update volume size detection method

Created by: pixiake

.status.capacity.storage is the actual persistent storage disk size. .spec.resources.requests.storage is the requested persistent storage disk size.

Some storage plugin generated persistent volumes that do not match the requested size, so the .spec.resources.requests.storage' should be filled with the existing .spec.resources.requests.storage` when upgrading.

.status.capacity.storage --> .spec.resources.requests.storage

Signed-off-by: pixiake guofeng@yunify.com