ixgbe: Move message handling routines into their own functions

Instead of trying to maintain one large monolithic function that handles
most of the different messages from the VF it makes sense to break the
message handling function up so that we can just go through one switch
statement and call the correct routine for a given message.

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>