Drivers: hv: vmbus: Introduce {lock,unlock}_requestor()

To abtract the lock and unlock operations on the requestor spin lock.
The helpers will come in handy in hv_pci.

No functional change.

Suggested-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20220419122325.10078-6-parri.andrea@gmail.com


Signed-off-by: Wei Liu <wei.liu@kernel.org>