CNN design added

[sfmth]

No description provided.

[bgoldbug]

The following changes are needed:

• Add LICENSE file to src/cnn
• Create a verilog.mk in src/cnn to allow for both make and make dev options
• Add a pre-generated cnn verilog file to src/cnn
• Remove the benchmark porting instructions pdf in the designs/ dir

[sfmth]

Requested changes made

[bgoldbug]

Requested changes to config.mk and verilog.mk

[bgoldbug]

All DESIGN_HOME vars need to be replaced with BENCH_DESIGN_HOME

[bgoldbug]

By default, we want the cnn.v file to exist outside of the dev directory, such that it's available for users without needing to run make dev initially.

• When I try to run make as the first command, it says: cnn.v is missing; using dev RTL. Run 'make dev' to regenerate and promote.
• It should instead use an existing cnn.v (existing without runningmake dev)

[sfmth]

This should fix those problems