net/mlx5e: Remove output device parameter from create encap header helpers definition

Passing output device parameter to the helper functions that deal with
creation of encapsulation headers is redundant. Output device parameter
can be defined inside those helpers, no need to pass it. Refactor the code by
removing the parameter from the function signature.

This patch doesn't change any functionality.

Signed-off-by: Hadar Hen Zion <hadarh@mellanox.com>
Reviewed-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>