mei: add mei_irq_compl_handler function

similar to read/write add also irq completion handler
that is called for the irq thread

rename missnamed mei_irq_complete_handler to
mei_cl_complete_handler as it operates on a single client

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>