Staging: line6: Fix no space before tabs in usbdefs.h

This patch fixes the following checkpatch.pl issues in usbdefs.h:
WARNING: no space before tabs
Signed-off-by: Monam Agarwal <monamagarwal123@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>