mei: drop me_client_presentation_num

me_client_presentation_num field is not used for any
particular purpose now, so it can be safely dropped.

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>