e1000e: rename e1000e_config_collision_dist() and call as function pointer

Rename e1000e_config_collision_dist() to
e1000e_config_collision_dist_generic() to signify the function is used for
more than one MAC-family type, and set and use it as a MAC ops function
pointer to be consistent with the driver design.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>