outdated README for benchmarks deleted

hpvm/test/dnn_benchmarks/README.md

-# Directory Structure
-
-* ./benchmarks: code corresponding to each benchmark
-  *  ./benchmarks/${BENCH_NAME}/bin/approximate.py: script for running autotuner
-  *  ./benchmarks/${BENCH_NAME}/Makefile: benchmark build script
-* ./common:
-  * ./common/include: include files
-  * ./common/bin/setup_tyler_paths.sh: modify paths to HPVM Build and SRC as per installation
-    * REQUIRED to run before building benchmarks 
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