Remove external/linux-tools-perf from the manifest.

Use system/extras/simpleperf instead.

default.xml

@@ -211,7 +211,6 @@
   <project path="external/libweave" name="platform/external/libweave" />
   <project path="external/libxml2" name="platform/external/libxml2" groups="pdk-cw-fs,pdk-fs,libxml2" />
   <project path="external/libyuv" name="platform/external/libyuv" groups="libyuv,pdk-cw-fs,pdk-fs" />
-  <project path="external/linux-tools-perf" name="platform/external/linux-tools-perf" groups="pdk-cw-fs,pdk-fs" />
   <project path="external/littlemock" name="platform/external/littlemock" groups="pdk-cw-fs,pdk-fs" />
   <project path="external/lld" name="platform/external/lld" groups="pdk-fs" />
   <project path="external/lldb" name="platform/external/lldb" groups="pdk-cw-fs,pdk-fs" />