sbgemm: spr: enlarge P to 256 for performance

param.h

@@ -1781,7 +1781,7 @@ USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 // But for AMX, they are not the same, set UNROLL_M = 32 to workaround
 #define SBGEMM_DEFAULT_UNROLL_N 16
 #define SBGEMM_DEFAULT_UNROLL_M 32
-#define SBGEMM_DEFAULT_P 192
+#define SBGEMM_DEFAULT_P 256
 #define SBGEMM_DEFAULT_Q 1024
 #define SBGEMM_DEFAULT_R sbgemm_r