USB: Add endpoint usage definitions to ch9.h

The endpoint usage field is described in the USB 2.0 specification,
chapter 9.6.6.

Also, move the sync type fields block down by some lines to reflect the
fact that these are also stuffed in bmAttributes.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Acked-by: Clemens Ladisch <clemens@ladisch.de>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>