LICENSES: Add Linux-OpenIB license text

LICENSES: Add Linux-OpenIB license text

The infiniband code uses a variant of the OpenIB license. This license is
BSD-2-Clause with the MIT disclaimer. The linux kernel uses this license
extensively throughout the driver subsystem since 2005. Note that the
OpenIB.org license is a true match to BSD-2-Clause.

The license text was copied from:

    https://spdx.org/licenses/Linux-OpenIB.html#licenseText

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>