mei: return error on notification request to a disconnected client

mei: return error on notification request to a disconnected client

[ Upstream commit 7c47d2ca0feca767479329da23523ed798acb854 ]

Request for a notification from a disconnected client will be ignored
silently by the FW but the caller should know that the operation hasn't
succeeded.

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