optimized param.h for POWER8

param.h

@@ -1978,12 +1978,12 @@ USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #define ZGEMM_DEFAULT_UNROLL_N 2
 
 #define SGEMM_DEFAULT_P  1280
-#define DGEMM_DEFAULT_P  768
+#define DGEMM_DEFAULT_P  640
 #define CGEMM_DEFAULT_P  640
 #define ZGEMM_DEFAULT_P  320
 
 #define SGEMM_DEFAULT_Q  640
-#define DGEMM_DEFAULT_Q  768
+#define DGEMM_DEFAULT_Q  640
 #define CGEMM_DEFAULT_Q  640
 #define ZGEMM_DEFAULT_Q  640