ehci: enable debugging code when CONFIG_DYNAMIC_DEBUG is set

The debugging code for ehci is enabled to run if the DEBUG flag is defined.
This patch enables the debugging code also when the kernel is configured
with dynamic debugging on.

Signed-off-by: Xenia Ragiadakou <burzalodowa@gmail.com>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>