This website gives a complete list of all AMD CPU/APU that are vulnerable to Meltdown/Spectre flaw. https://www.techarp.com/guides/complete-meltdown-spectre-cpu-list/2/
None of AMD CPU/APU have the Meltdown Flaw only the Spectre flaws.
Your Motherboard's Manufacturer should have updated the BIOS to fix the Spectre flaw of the CPU. Need to be sure you have the latest BIOS update on your motherboard to be sure it has the fix to the Spectre Flaw.
From AMD Security concerning the Spectre Flaw and fixes: AMD Processor Security | AMD
Thanks for your clarification !