ice: move VSI configuration outside repr setup

It is needed because subfunction port representor shouldn't configure
the source VSI during representor creation.

Move the code to separate function and call it only in case the VF port
representor is being created.

Signed-off-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Tested-by: Sujai Buvaneswaran <sujai.buvaneswaran@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>