mei: introduce host client uninitialized state

Introduce a new host client state, MEI_FILE_UNINITIALIZED,
to distinguish client objects that was unlinked,
but not destroyed and can be linked again.

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>