media: mceusb: Fix potential out-of-bounds shift

When processing a MCE_RSP_GETPORTSTATUS command, the bit index to set in
ir->txports_cabled comes from response data, and isn't validated.

As ir->txports_cabled is a u8, nothing should be done if the bit index
is greater than 7.

Cc: stable@vger.kernel.org
Reported-by:  <syzbot+ec3b3128c576e109171d@syzkaller.appspotmail.com>
Signed-off-by: James Reynolds <jr@memlen.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>