nitro_enclaves: Define enclave info for internal bookkeeping

The Nitro Enclaves driver keeps an internal info per each enclave.

This is needed to be able to manage enclave resources state, enclave
notifications and have a reference of the PCI device that handles
command requests for enclave lifetime management.

Changelog

v9 -> v10

* Update commit message to include the changelog before the SoB tag(s).

v8 -> v9

* Add data structure to keep references to both Nitro Enclaves misc and
PCI devices.

v7 -> v8

* No changes.

v6 -> v7

* Update the naming and add more comments to make more clear the logic
of handling full CPU cores and dedicating them to the enclave.

v5 -> v6

* Update documentation to kernel-doc format.
* Include in the enclave memory region data structure the user space
address and size for duplicate user space memory regions checks.

v4 -> v5

* Include enclave cores field in the enclave metadata.
* Update the vCPU ids data structure to be a cpumask instead of a list.

v3 -> v4

* Add NUMA node field for an enclave metadata as the enclave memory and
CPUs need to be from the same NUMA node.

v2 -> v3

* Remove the GPL additional wording as SPDX-License-Identifier is
already in place.

v1 -> v2

* Add enclave memory regions and vcpus count for enclave bookkeeping.
* Update ne_state comments to reflect NE_START_ENCLAVE ioctl naming
update.

Reviewed-by: Alexander Graf <graf@amazon.com>
Signed-off-by: Alexandru-Catalin Vasile <lexnv@amazon.com>
Signed-off-by: Andra Paraschiv <andraprs@amazon.com>
Link: https://lore.kernel.org/r/20200921121732.44291-4-andraprs@amazon.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>