PCI: hv: Remove bus device removal unused refcount/functions

PCI: hv: Remove bus device removal unused refcount/functions

With the new method of flushing/stopping the workqueue before doing bus
removal, the old mechanism of using refcount and wait for completion
is no longer needed. Remove those dead code.

Link: https://lore.kernel.org/r/1620806809-31055-1-git-send-email-longli@linuxonhyperv.com
Signed-off-by: Long Li <longli@microsoft.com>
[lorenzo.pieralisi@arm.com: Reworded subject]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>