[PATCH] USB UHCI: Detect invalid ports

This patch changes the way uhci-hcd detects valid ports.  The
specification doesn't mention any way to find out how many ports a
controller has, so the driver has to use some heuristics, reading the port
status and control register and deciding whether the value makes sense.
With this patch the driver will recognize a typical failure mode (all bits
set to one) for nonexistent ports and won't assume there are always at
least 2 ports -- such an assumption seems silly if the heuristics have
already shown that the ports don't exist.

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