USB: digi_acceleport: do sanity checking for the number of ports

[ Upstream commit 5a07975a ]

The driver can be crashed with devices that expose crafted descriptors
with too few endpoints.

See: http://seclists.org/bugtraq/2016/Mar/61



Signed-off-by: Oliver Neukum <ONeukum@suse.com>
[johan: fix OOB endpoint check and add error messages ]
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: Sasha Levin <sasha.levin@oracle.com>