EHCI: add debugging message to ehci_bus_suspend

This patch (as848) adds a useful little debugging message to let us
know when ehci-hcd's bus_suspend method runs.  The other HCDs have
similar messages; now ehci-hcd doesn't need to feel left out.

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