nvme-pci: split the probe and reset handlers v2

[Christoph Hellwig]

Hi all,

this series split the nvme-pci probe handler to be separate from the reset
handler.  I've been wanting to do that for a while, but the bug report from
Gerd that was caused by confusing about the controller state in the reset
state required it to be expedited.

Changes since v1:
 - switch back from IS_ENABLED for the SED_OPAL code to prevent a warning
   when it is disabled.
 - rename nvme_pci_alloc_ctrl to nvme_pci_alloc_dev
 - allow initializating shadow doorbell buffers during reset
 - simplify HMB setup a bit
 - shutdown the controller on reset failure

Diffstat:
 host/apple.c  |    2 
 host/core.c   |   39 ++++-
 host/fc.c     |    2 
 host/nvme.h   |    7 
 host/pci.c    |  413 ++++++++++++++++++++++++++++------------------------------
 host/rdma.c   |    2 
 host/tcp.c    |    2 
 target/loop.c |    2 
 8 files changed, 240 insertions(+), 229 deletions(-)