drivers: usb: kinetis: fixup endpoint config, stall and read

This patch fixes some bugs found during testing with testusb from
linux kernel.

An unresolved issue is that the stack is not fast enough
to stall (if necessary) the control endpoint during Setup Stage.
This might require a API change so that the usb device stack
can explicit allow the driver to resume token processing.

Signed-off-by: Johann Fischer <j.fischer@phytec.de>