Staging: epl: remove compiler warning from SharedBuff.c

Yeah, it's a buffer, but this sure can't hurt as it's not easy to unwind
where it's coming from.

Cc: Daniel Krueger <daniel.krueger@systec-electronic.com>
Cc: Ronald Sieber <Ronald.Sieber@systec-electronic.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>