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