ixgbevf: make use of the dev pointer in the ixgbevf_ring struct

This patch cleans up the code by removing the adapter structure as
parameter from multiple functions. The adapter structure was previously
being used to access the dev pointer, but this can also be done via the
ixgbevf_ring structure. This way we can drop the adapter as parameter from
these functions.

This patch also includes small cleanups in some error code paths.

Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>