mei: define dma ring buffer sizes for PCH12 HW and newer

Define dma ring buffer sizes for PCH12 (CLN HW and newer)

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>