Restored framework as a submodule

- git submodule add https://github.com/Mbed-TLS/mbedtls-framework framework
- git submodule init
- pushd framework && git checkout cab0c5 && popd
- git add framework

Signed-off-by: Minos Galanakis <minos.galanakis@arm.com>
diff --git a/framework b/framework
new file mode 160000
index 0000000..cab0c5f
--- /dev/null
+++ b/framework
@@ -0,0 +1 @@
+Subproject commit cab0c5fe19d5747cb9603552b80ebe64b9c67fdd