USB: serial: remove CONFIG_USB_DEBUG from sierra and option drivers

These drivers should not be relying on CONFIG_USB_DEBUG.  By doing this,
it prevents users of kernels that do not enable this option from
enabling debugging in these drivers, unlike all other usb-serial
drivers.

Cc: Matthias Urlichs <smurf@smurf.noris.de>
Cc: Kevin Lloyd <klloyd@sierrawireless.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>