Adding correct cache sizes for PPC architecture.

Eigen/src/Core/products/GeneralBlockPanelKernel.h

diff --git a/Eigen/src/Core/products/GeneralBlockPanelKernel.h b/Eigen/src/Core/products/GeneralBlockPanelKernel.h
index 2ae8ece..d0dc14d 100644
--- a/Eigen/src/Core/products/GeneralBlockPanelKernel.h
+++ b/Eigen/src/Core/products/GeneralBlockPanelKernel.h
@@ -35,6 +35,10 @@
 const std::ptrdiff_t defaultL1CacheSize = 32*1024;
 const std::ptrdiff_t defaultL2CacheSize = 256*1024;
 const std::ptrdiff_t defaultL3CacheSize = 2*1024*1024;
+#elif EIGEN_ARCH_PPC
+const std::ptrdiff_t defaultL1CacheSize = 64*1024;
+const std::ptrdiff_t defaultL2CacheSize = 512*1024;
+const std::ptrdiff_t defaultL3CacheSize = 4*1024*1024;
 #else
 const std::ptrdiff_t defaultL1CacheSize = 16*1024;
 const std::ptrdiff_t defaultL2CacheSize = 512*1024;