media: flexcop-usb: fix endpoint sanity check

commit bca243b1ce0e46be26f7c63b5591dfbb41f558e5 upstream.

commit 1b976fc6d684 ("media: b2c2-flexcop-usb: add sanity checking") added
an endpoint sanity check to address a NULL-pointer dereference on probe.
Unfortunately the check was done on the current altsetting which was later
changed.

Fix this by moving the sanity check to after the altsetting is changed.

Fixes: 1b976fc6d684 ("media: b2c2-flexcop-usb: add sanity checking")
Cc: Oliver Neukum <oneukum@suse.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>