package/stress-ng: really remove patch merged upstream

Should have been removed in commit 27bce5fc8e (package/stress-ng: bump
to version 0.09.39) but was left as an empty file.

Signed-off-by: Carlos Santos <casantos@datacom.com.br>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>