This was set to netascii by accident and is definitely not what we want when
transfering over a kernel.

BUG=chrome-os-partner:16688
TEST=Built and booted into the netboot payload on Link. The payload size is
now correct. Dumped some of the file's contents as the were loaded by the
firmware and verified that the it wasn't being munged any more.
BRANCH=None

Change-Id: I3da3a88c3fa766730a2118d5e16327b96b099d83
Signed-off-by: Gabe Black <gabeblack@google.com>