net/mlx5: SD, add L2 table silent mode query support

net/mlx5: SD, add L2 table silent mode query support

Add mlx5_fs_cmd_query_l2table_silent() to query the current silent mode
state from firmware. This allows detecting if firmware has already put
secondary devices into silent mode.

During SD group registration, query the silent mode of each device. If
a device is already in silent mode (set by firmware), record this in
the fw_silents_secondaries flag and use it to help determine the
primary/secondary roles.

When fw_silents_secondaries is set, skip the driver-initiated silent
mode set/unset operations since firmware manages this state. This
handles configurations where firmware persistently silences secondary
devices.

Signed-off-by: Shay Drory <shayd@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://patch.msgid.link/20260612113904.537595-6-tariqt@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>