ice: Refactor ice_ena_vf_mappings to split MSIX and queue mappings

Currently ice_ena_vf_mappings() does all of the VF's MSIX and queue
mapping in one function. This makes it hard to digest. Fix this by
creating a new function for enabling MSIX mappings and one for enabling
queue mappings.

Also, rename some variables in the functions for clarity.

Signed-off-by: Brett Creeley <brett.creeley@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>