ddb: use _FLAGS command macros where appropriate

[mhorne]

Summary

Some command definitions were forced to use DB_FUNC in order to specify
their required flags, CS_OWN or CS_MORE. Use the new macros to simplify
these.

[jhb]

I feel like there's some custom ones in sys/dev/cxgbe as well. They use a custom table though, so maybe that doesn't quite work for this.