drivers/staging/line6/driver.c: Drop unneeded put functions.

This seems to be the result of patches ab366c1a and 1027f476 crossing each
other.  Patch ab366c1a adds calls to usb_put_intf and usb_put_dev at the
end of the function line6_probe, in the error handling code, while patch
1027f476 moves the calls to the corresponding get function from the
beginning to the end of line6_probe, making the calls to put in the error
handling code unnecessary.

// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>