media: flexcop-usb: clean up URB initialisation

Clean up URB initialisation somewhat by introducing a temporary variable
and separating declaration and non-trivial initialisation.

Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20220822151456.27178-3-johan@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>