ixgbe: Merge RSS and flow director ring register caching and configuration

There are really only 3 modes that can control the number of queues.  Those
are RSS, DCB, and VMDq/SR-IOV.  Currently we have things much more broken
up than they need to be for how we are configuring the rings.  In order to
try and straiten some of this out I am going to start merging similar
functionality into single functions.  To start with I am merging the Flow
Director ring configuration into the RSS ring configuration since Flow
Director cannot function with DCB or SR-IOV.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>