Clean up STACKSIZE redefinition

Author: martin-frbg

kernel/power/dtrmm_kernel_16x4_power8.S

@@ -82,7 +82,6 @@ USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #endif
 
 #ifdef __64BIT__
-#define STACKSIZE 320
 #define STACKSIZE 520
 #define ALPHA_SP   296+200(SP)
 #define FZERO	304+200(SP)