ocxl: Add get_metadata IOCTL to share OCXL information to userspace

ocxl: Add get_metadata IOCTL to share OCXL information to userspace

BugLink: http://bugs.launchpad.net/bugs/1755161
Some required information is not exposed to userspace currently (eg. the
PASID), pass this information back, along with other information which
is currently communicated via sysfs, which saves some parsing effort in
userspace.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Acked-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
(cherry picked from commit 07c5ccd70ad702e561fcda8e4df494f098a42742)
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>