Clean up STACKSIZE redefinition

kernel/power/strmm_kernel_16x8_power8.S

@@ -12,7 +12,7 @@ the documentation and/or other materials provided with the
 distribution.
 3. Neither the name of the OpenBLAS project nor the names of
 its contributors may be used to endorse or promote products
-derived from this software without specific prior written permission.
+derived from this software without specific prior written permission.  
 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
@@ -82,7 +82,6 @@ USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #endif
 
 #ifdef __64BIT__
-#define STACKSIZE 340
 #define STACKSIZE 540
 #define ALPHA_SP   296+200(SP)
 #define FZERO	304+200(SP)