Fix bug in tfa tar components for cloning sources

Change-Id: Ib6682e3cc99e7d86fb4fb6a21deecadab66148f9
Signed-off-by: saurom01 <saul.romero@arm.com>
diff --git a/script/build_bmcov.sh b/script/build_bmcov.sh
index 0ba1d29..8e24f5e 100755
--- a/script/build_bmcov.sh
+++ b/script/build_bmcov.sh
@@ -65,6 +65,7 @@
                     "type": "http",
                     "URL":  "$mbedtls_archive",
                     "COMPRESSION": "xz",
+                    "EXTRA_PARAMS": "--strip-components=1",
                     "LOCATION": "mbedtls"
                     }
                 ]