pm80xx : Fix missing NULL pointer checks and memory leaks

Checking return value for the memory allocattion and freeing it
while exiting the function

Signed-off-by: Viswas G <Viswas.G@pmcs.com>
Signed-off-by: Suresh Thiagarajan <Suresh.Thiagarajan@pmcs.com>
Reviewed-by: Tomas Henzl <thenzl@redhat.com>
Acked-by: Jack Wang <xjtuwjp@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>