nitro_enclaves: Add Kconfig for the Nitro Enclaves driver

nitro_enclaves: Add Kconfig for the Nitro Enclaves driver

Add kernel config entry for Nitro Enclaves, including dependencies.

Changelog

v9 -> v10

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

v8 -> v9

* No changes.

v7 -> v8

* No changes.

v6 -> v7

* Remove, for now, the dependency on ARM64 arch. x86 is currently
  supported, with Arm to come afterwards. The NE kernel driver can be
  built for aarch64 arch.

v5 -> v6

* No changes.

v4 -> v5

* Add arch dependency for Arm / x86.

v3 -> v4

* Add PCI and SMP dependencies.

v2 -> v3

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

v1 -> v2

* Update path to Kconfig to match the drivers/virt/nitro_enclaves
  directory.
* Update help in Kconfig.

Reviewed-by: Alexander Graf <graf@amazon.com>
Signed-off-by: Andra Paraschiv <andraprs@amazon.com>
Link: https://lore.kernel.org/r/20200921121732.44291-15-andraprs@amazon.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>