net/mlx5: E-switch, make query inline mode a static function

mlx5_eswitch_inline_mode_get() is used only in eswitch_offloads.c.
Hence, make it static and adjacent to its caller function.

Reviewed-by: Roi Dayan <roid@mellanox.com>
Reviewed-by: Bodong Wang <bodong@mellanox.com>
Signed-off-by: Parav Pandit <parav@mellanox.com>
Reviewed-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>