Drivers: hv: utils: Continue to poll VSS channel after handling requests.

Drivers: hv: utils: Continue to poll VSS channel after handling requests.

Multiple VSS_OP_HOT_BACKUP requests may arrive in quick succession, even
though the host only signals once. The driver wass handling the first
request while ignoring the others in the ring buffer. We should poll the
VSS channel after handling a request to continue processing other requests.

Signed-off-by: Alex Ng <alexng@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Orabug: 27426063
(cherry picked from commit 497af84b81b98b27e9ba7aebb8a373412e328497)
Signed-off-by: Jack Vogel <jack.vogel@oracle.com>
Reviewed-by: Ashok Vairavan <ashok.vairavan@oracle.com>