USB: mos7840: remove unused code

There is old, unused code that is #defined out by the use of NOTMOS7840
and NOTMCS7840 - these are not defined anywhere.

If NOTMOS7840 is defined then the code will break on null pointer
dereferences on mos7840_port. So the code is currently unused, and
broken anyway, so why not just remove it.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Johan Hovold <johan@kernel.org>