USB: add ep->enable

This patch (as944) adds an explicit "enabled" field to the
usb_host_endpoint structure and uses it in place of the current
mechanism.  This is merely a time-space tradeoff; it makes checking
whether URBs may be submitted to an endpoint simpler.  The existing
mechanism is efficient when converting urb->pipe to an endpoint
pointer, but it's not so efficient when urb->ep is used instead.

As a side effect, the procedure for enabling an endpoint is now a
little more complicated.  The ad-hoc inline code in usb.c and hub.c
for enabling ep0 is now replaced with calls to usb_enable_endpoint,
which is no longer static.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/include/linux/usb.h b/include/linux/usb.h
index 105e3e9..818a1b4 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -52,6 +52,7 @@
  * @ep_dev: ep_device for sysfs info
  * @extra: descriptors following this endpoint in the configuration
  * @extralen: how many bytes of "extra" are valid
+ * @enabled: URBs may be submitted to this endpoint
  *
  * USB requests are always queued to a given endpoint, identified by a
  * descriptor within an active interface in a given USB configuration.
@@ -64,6 +65,7 @@
 
 	unsigned char *extra;   /* Extra descriptors */
 	int extralen;
+	int enabled;
 };
 
 /* host-side wrapper for one interface setting's parsed descriptors */