ice: add a function to initialize vf entry

Some of the initialization code for Single Root IOV VFs will need to be
reused when we introduce Scalable IOV. Pull this code out into a new
ice_initialize_vf_entry helper function.

Co-developed-by: Harshitha Ramamurthy <harshitha.ramamurthy@intel.com>
Signed-off-by: Harshitha Ramamurthy <harshitha.ramamurthy@intel.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Marek Szlosek <marek.szlosek@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>