fix atomic limits check

[Christoph Hellwig <hch@lst.de>]

Hi all,

this series tries to fix the atomics limit check to limit it to
the per-controller values and to the controller probing.

I think this should solve the root cause of the report from Yi Zhang,
but needs new verification.

Diffstat:
 core.c |   84 ++++++++++++++++++++++++++++++-----------------------------------
 nvme.h |    3 --
 2 files changed, 40 insertions(+), 47 deletions(-)