USB: EHCI: fix remote-wakeup support for ARC/TDI core

This patch (as1147) fixes the remote-wakeup support for EHCI
controllers using the ARC/TDI "embedded-TT" core.  These controllers
turn off the RESUME bit by themselves when a port resume is complete;
hence we need to keep separate track of which ports are suspended or
in the process of resuming.

The patch also makes a couple of small improvements in ehci_irq(),
replacing reads of the command register with the value already stored
in a local variable.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Tested-by: Thomas Reitmayr <treitmayr@devbase.at>
CC: David Brownell <david-b@pacbell.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>