[PATCH] usb doc: fix kernel-doc warning

usb/core/buffer.c doesn't export any symbols, so it should use
!I instead of !E to eliminate this warning message:

Warning(/var/linsrc/linux-2614-rc4//drivers/usb/core/buffer.c): no structured comments found
Signed-off-by: NRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Documentation/DocBook/usb.tmpl

@@ -291,7 +291,7 @@
 
 !Edrivers/usb/core/hcd.c
 !Edrivers/usb/core/hcd-pci.c
-!Edrivers/usb/core/buffer.c
+!Idrivers/usb/core/buffer.c
     </chapter>
 
     <chapter>