enabled optimized sgemv kernels for piledriver

kernel/x86_64/KERNEL.HASWELL

@@ -1,4 +1,4 @@
-SGEMVNKERNEL = sgemv_n_4.c
+SGEMVNKERNEL = sgemv_n.c
 SGEMVTKERNEL = sgemv_t.c
 
 DGEMVNKERNEL = dgemv_n.c

kernel/x86_64/KERNEL.PILEDRIVER

@@ -1,5 +1,5 @@
-SGEMVNKERNEL = sgemv_n.c
-SGEMVTKERNEL = sgemv_t.c
+SGEMVNKERNEL = sgemv_n_4.c
+SGEMVTKERNEL = sgemv_t_4.c
 
 ZGEMVNKERNEL = zgemv_n_dup.S
 ZGEMVTKERNEL = zgemv_t.S

kernel/x86_64/sgemv_t_4.c

@@ -30,7 +30,7 @@ USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #if defined(NEHALEM)
 #include "sgemv_t_microk_nehalem-4.c"
-#elif defined(BULLDOZER)
+#elif defined(BULLDOZER) || defined(PILEDRIVER)
 #include "sgemv_t_microk_bulldozer-4.c"
 #elif defined(SANDYBRIDGE)
 #include "sgemv_t_microk_sandy-4.c"