openssh: Remove BSD-4-clause contents completely from codebase

Below upstream commit removed BSD-4-Clause from the LICENSE variable,
Link: https://git.yoctoproject.org/poky/commit/?id=2c86f586d55d0f6b99053e3e4d14c9ee36fa8aa8
But actually if we check from the source code of the openssh for this
version (8.9p1), there are some files (openbsd-compat/libressl-api-compat.c)
still affected.

As upstream removed this BSD-4-clause license, there are still some files
has this license. Below file is affected by this BSD-4-clause contents when
the below command is executed
grep -rl "All advertising materials mentioning features or use of this software" *|grep -v \.1|grep -v \.5|grep -v \.8 | sort
openbsd-compat/libressl-api-compat.c

All advertising materials mentioning features or use of this software

Reason for backporting is some of the product restrict the BSD-4-Clause usage and the purpose of this commit is
to completely remove the BSD-4-Clause license from the openssh.

When checked in the master branch, openssh upstream removes the bsd-4 license compeletely from this commit
https://github.com/openssh/openssh-portable/commit/7280401bdd77ca54be6867a154cc01e0d72612e0


Hence Backport this commit completely to remove license of BSD-4-clause contents from code. Hunks are refreshed.

Signed-off-by: Riyaz Khan <Riyaz.Khan@kpit.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
(cherry picked from commit d9045a7b)
Signed-off-by: Steve Sakoman <steve@sakoman.com>