Add building OpenSSL as part of build-arm-tf.sh

Since version 2.7 Arm-TF requires OpenSSL version 3.0 or higher to
be built.
This patch adds building OpenSSL locally (as part of build-arm-tf.sh)
and makes necessary changes for a successful build of the stack.

Signed-off-by: Patrik Berglund <patrik.berglund@arm.com>
Change-Id: Ibaf85a8992bbd227804a92c3436be20f90034223