ice: make representor code generic

Keep the same flow of port representor creation, but instead of general
attach function create helpers for specific representor type.

Store function pointer for add and remove representor.

Type of port representor can be also known based on VSI type, but it
is more clean to have it directly saved in port representor structure.

Add devlink lock for whole port representor creation and destruction.

Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Wojciech Drewek <wojciech.drewek@intel.com>
Signed-off-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Tested-by: Rafal Romanowski <rafal.romanowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>