nvme: fix bogus kzalloc() return check in nvme_init_effects_log()

nvme_init_effects_log() returns failure when kzalloc() is successful,
which is obviously wrong and causes failures to boot. Correct the
check.

Fixes: d4a95ade ("nvme: Add error path for xa_store in nvme_init_effects")
Signed-off-by: Jens Axboe <axboe@kernel.dk>