e_comp_object: Set null to data of image object if there is no data in pixmap.
e_comp_object: Set null to data of image object if there is no data in pixmap.

this patch is to avoid crash of enlightenment, when access the data of buffer
which is already destroyed.

Change-Id: Ieb812e9bf551d4856565df01274a5489df8b5ef5

tizenorg/platform.upstream.enlightenment,tizenorg/platform.upstream.enlightenment,tizenorg/platform.upstream.enlightenment