Revert Coverity project name change

Although Coverity have now changed their URL to point at the new
project, they did not change the project name, it would seem.

Signed-off-by: Paul Elliott <paul.elliott@arm.com>
diff --git a/.travis.yml b/.travis.yml
index 7b72515..67cb3ca 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -65,7 +65,7 @@
     - gnutls-bin
   coverity_scan:
     project:
-      name: "Mbed-TLS/mbedtls"
+      name: "ARMmbed/mbedtls"
     notification_email: support-mbedtls@arm.com
     build_command_prepend:
     build_command: make