cleanup: use switch/case for genVolFromVolID() error checking
cleanup: use switch/case for genVolFromVolID() error checking

By using switch/case it is easier to follow the error checking of the
genVolFromVolID() function. In case a new error is added as a return of
the function, it will be simpler to add checking for it.

Signed-off-by: Niels de Vos <7bda0c0ee7f47171cc808e9e60292cbc5d8140dd@redhat.com>

ceph/ceph-csi,ceph/ceph-csi,ceph/ceph-csi,ceph/ceph-csi