USB: Standardize inclusion protection and add where missing.

For the header files in include/linux/usb, add missing multiple
inclusion protection and standardize what's already there.  The
apparent standards:

  * macro name of __LINUX_USB_headerfile_H
  * inclusion protection placed after leading comment block
  * macro name added as a comment on the final #endif
  * any obvious trivial whitespace cleanup associated with the above

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>