The patch contains following changes:
- In conditional checks, always check for NULL or 0 instead of negating values
- Use malloc and free explicitely, instead of ENA_MEM_FREE and ENA_MEM_FREE (the dmadev passed to macro is never used, and could be a little misleading)
- Always check for NULL after calling malloc (few checks were missing)
- Rework naming of the goto tags in ena_attach() for consistency
- Fix error handling in ena_attach() - few goto instructions were leading to the wrong tag
- Destroy MMIO req read request if attach failed
- Remove checking for NULL after calling malloc with M_WAITOK flag