Maybe? But a few things count against that hypothesis. Elephants are already very mobile animals, so they can simply move away if they don't like the smell; dislike of the smell would, you'd think, drive them to move away rather than remaining with the corpse, moving it around, and trumpeting loudly. Secondly, do elephants do that with other animal corpses they discover in their travels? We would expect not, though this would need observation and trials to find out for sure. Thirdly, does this way of burying the corpse make it more difficult for scavenging animals to discover the corpse? If so, that counts for the other hypothesis.