intel_synth: Fix help message
intel_synth: Fix help message

cyclonev has been a "supported" family since the initial commit. The old
commit message suggested to use a10gx which is incorrect.

Aside from the obvious lack of functional change due to this just being
a help message, users who were previously using "a10gx" for "cyclonev" will
also have no functional change by using "cyclonev" instead.

Signed-off-by: Ben Widawsky <73675debcd8a436be48ec22211dcf44fe0df0a64@bwidawsk.net>

cliffordwolf/yosys,cliffordwolf/yosys,YosysHQ/yosys,antmicro/yosys,antmicro/yosys,antmicro/yosys,cliffordwolf/yosys,cliffordwolf/yosys,cliffordwolf/yosys,cliffordwolf/yosys,YosysHQ/yosys,SymbiFlow/yosys,antmicro/yosys,cliffordwolf/yosys,antmicro/yosys,antmicro/yosys,antmicro/yosys,SymbiFlow/yosys,SymbiFlow/yosys,SymbiFlow/yosys,SymbiFlow/yosys,SymbiFlow/yosys,YosysHQ/yosys,cliffordwolf/yosys,YosysHQ/yosys,YosysHQ/yosys,SymbiFlow/yosys,YosysHQ/yosys,SymbiFlow/yosys,YosysHQ/yosys,antmicro/yosys,cliffordwolf/yosys,YosysHQ/yosys