[PATCH v2] doc: add deprecation notice for iavf devarg auto reconfig

[Ciara Loftus <ciara.loftus@intel.com>]

The `auto_reconfig` devarg in the iavf driver is enabled by default and the
case for ever disabling it is weak. When disabled, it means the user is
requesting the driver not to restore settings (unicast/multicast
promiscuous modes) when recovering from a reset. The use case where this
might be desired is during a VF initiated reset where the user initiates
the reset and wants the VF brought back up in an untouched state. That
scenario can be facilitated by extending the `rte_pmd_iavf_reinit` API
rather than relying on this devarg, so it should be safe to remove the
devarg.

Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>
---
v2:
* Shortened deprecation note
---
 doc/guides/rel_notes/deprecation.rst | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/doc/guides/rel_notes/deprecation.rst b/doc/guides/rel_notes/deprecation.rst
index f5c12cc747..910feb7cf2 100644
--- a/doc/guides/rel_notes/deprecation.rst
+++ b/doc/guides/rel_notes/deprecation.rst
@@ -159,3 +159,9 @@ Deprecation Notices
 * net/iavf: The dynamic mbuf field used to detect LLDP packets on the
   transmit path in the iavf PMD will be removed in a future release.
   After removal, only packet type-based detection will be supported.
+
+* net/iavf: The ``auto_reconfig`` devarg is deprecated and will be removed
+  in a future release. It allows disabling the automatic restoration of
+  device settings after a VF reset, but this is of questionable value
+  since most applications expect their settings to be preserved
+  transparently across a reset.
-- 
2.43.0