volgroup and vgpattern should not be mandatory for scheduling

[abhilashshetty04]

Following are the current behavior.

volgroup or vgpattern are mandatory patten in sc for lvm localpv to provision volume successfully. If only one of this pattern is specified, Then lvm-localpv assumes that the vg matching the pattern is available on all lvmnodes. Otherwise, User have to explicitly define which node has spcified vg using node topology. Its not easy User experience.

I'm suggesting following change:

1. Make volgroup and vgpattern not a mandatory paramater in storage class for volume provisioning. If user have not provided anyof these 2 params and no topology constraint. Schedular can place lvmvolume on any node any vg.

2. If user specified volgroup/vgpattern then provisioner should take that into consideration. if no topology specified, Provisioner should not expect vg to be present on all node. It should try to find any node having the vg specified. If it can accomodate the vg then it should just create CR for that node.

3. If user creates sc with volgroup/vgpattern only one some nodes, has node topologies also set to a particular node/s. Then strictly adhere to that.