Revert "avfilter/vf_noise: dont corrupt the picture outside width x height"

This reverts commit 51dab60c7b91a21ec280c7d3042aa8350aae048f.

this fixed nothing, and was just the result of assuming that the
variable named linesize was the linesize. Its not, its the width
in bytes which was already correct.

Found-by: durandal_1707
