Merge branch 'net-mlx-migrate-to-new-get_rx_ring_count-ethtool-api'

Breno Leitao says:

====================
net: mlx: migrate to new get_rx_ring_count ethtool API

This series migrates the mlx4 and mlx5 drivers to use the new
.get_rx_ring_count() callback introduced in commit 84eaf4359c36 ("net:
ethtool: add get_rx_ring_count callback to optimize RX ring queries").

Previously, these drivers handled ETHTOOL_GRXRINGS within the
.get_rxnfc() callback. With the dedicated .get_rx_ring_count() API, this
handling can be extracted and simplified.

For mlx5, this affects both the ethernet and IPoIB drivers. The
ETHTOOL_GRXRINGS handling was previously kept in .get_rxnfc() to support
"ethtool -x" when CONFIG_MLX5_EN_RXNFC=n, but this is no longer
necessary with the new dedicated callback.

Note: The mlx4 changes are compile-tested only, while mlx5 changes were
properly tested.
====================

Link: https://patch.msgid.link/20251113-mlx_grxrings-v1-0-0017f2af7dd0@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>