evas/image: fix broken auto_fill mechanism when manually changing fill

evas/image: fix broken auto_fill mechanism when manually changing fill

Summary:
if auto_fill is set (which is the default for image objects), manually setting
the fill for the image would previously only persist until the image was resized,
at which point the auto_fill would activate and re-set the image's fill to be
the same as the image's object geometry

this fixes the auto_fill behavior to stop modifying the image's fill geometry
if the fill is manually changed by the user, which fixes using fill on most
image objects

@fix

Reviewers: cedric, Hermet

Reviewed By: cedric

Subscribers: #reviewers, #committers

Tags: #efl

Differential Revision: https://phab.enlightenment.org/D8879