Add the pvscsi driver to the tree.
This driver allows to usage of the paravirt SCSI controller
in VMware products like ESXi. The pvscsi driver provides a
substantial performance improvement in block devices versus
the emulated mpt and mps SCSI/SAS controllers.
Error handling in this driver has not been extensively tested
Submitted by: email@example.com
Sponsored by: VMware, Panzura
Differential Revision: D18613