mem-ruby: Allow SLICC symbols to have no description.

Updated the SLICC `Symbol` class to return an empty string when its
`desc` property is read.

The SLICC language does not require a symbol to have a `desc` for
protocol generation, but the generation of SLICC HTML documentation
expects a `desc` and will fail if it is not present.

Change-Id: I07cc0ab805520eb74f86c6ea8036abb7354b10a9
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/60870
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
1 file changed