usb: chipidea: convert debug entries in sysfs to debugfs

Currently, we have a bunch of files in sysfs that display all sorts of
debugging information for the device controller, so they have to move to
debugfs where they belong. The "registers" interface have been removed,
since it doesn't fit into the current driver design as is and it's hardly
a good idea to touch the registers from userspace anyway.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>