As part of the authentication flow for Dynamic Boost Control, the calling
software will need to send a uid used in all of its future
communications.

Add support for another IOCTL call to let userspace software set this up.
Acked-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>