mei: revamp client connection

Simplify connect state machine by changing the logic around
Connection request in progress - only check if we have a callback in
relevant queue.
Extract common code into mei_cl_send_connect() function

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