Coverity (1769) found the following problem: if the erase counter
overflow check triggers, ec_hdr is leaked.

Moving the allocation after the overflow check should take care of it.
Signed-off-by: Florin Malita <fmalita@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>