Add ECDSA-P256 key in PKCS#8 format
The ring crypto library used by the simulator only accepts PEM keys in
PKCS#8 format; this provides a conversion of the original bundled key.
```
$ openssl pkcs8 -topk8 -nocrypt -in ../root-ec-p256.pem -out ../root-ec-p256-pkcs8.pem
```
Signed-off-by: Fabio Utzig <utzig@apache.org>
diff --git a/root-ec-p256-pkcs8.pem b/root-ec-p256-pkcs8.pem
new file mode 100644
index 0000000..42a1e0e
--- /dev/null
+++ b/root-ec-p256-pkcs8.pem
@@ -0,0 +1,5 @@
+-----BEGIN PRIVATE KEY-----
+MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQg15jVL4MBJDvTVCt+
+Ve1MdGEZALD5UFqCT+Ho7AY7z/GhRANCAAQqy0A86P7tW6RJlaGpHa7o274ZN80U
++y8kVzfllTmI2ZS51lrr183VMIrW/kiySmqBDuXwfYtoNMw6avxTjvrB
+-----END PRIVATE KEY-----