USB: cdc-acm: check for valid interfaces

We need to check that we have both a valid data and control inteface for both
types of headers (union and not union.)

References: https://bugzilla.kernel.org/show_bug.cgi?id=83551
Reported-by: Simon Schubert <2+kernel@0x2c.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --cc drivers/usb/class/cdc-acm.c
Simple merge