Error message is too generic when falling back to CPULM when not meeting the GPU minspec

1. Have a below minspec card
2. Try to bake with GPULM
3. Fallback doesn't say why

We should probably get rid of "filtering device for lightmapping" and just disable the GPULM.

 

Seen on 2022.2 by a user with a 2GB card.

Should be fixed in all versions (including 2023).