Add mips64 kernel

This is to support 64bit mips CPU.
Built with following command:
${ANDROID_BUILD_TOP}/external/qemu/distrib/build-kernel.sh --arch=mips64 --gcc-version=4.9

Change-Id: I045511bb5be8b127afab797ea029fce859e45467
diff --git a/mips64/README b/mips64/README
new file mode 100644
index 0000000..8a751ca
--- /dev/null
+++ b/mips64/README
@@ -0,0 +1,6 @@
+This directory contains kernel images to be used with the Android emulator
+program, for the mips64 CPU architecture. It was built with the build-kernel.sh
+script. For more details, read:
+
+  $AOSP/external/qemu/docs/ANDROID-KERNEL.TXT
+