test: align ec_pub public keyfile with its ec_prv.sec1 counterpart

This change affects:
- both PEM and DER files, since they contain the same public key
  only in different formats
- "ec_pub.comp.pem" since it's the same as "ec_pub.pem" but in
  compressed format

The makefile was also updated accordingly to reflect these
dependencies.

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/tests/data_files/ec_pub.comp.pem b/tests/data_files/ec_pub.comp.pem
index a3742a3..55fac08 100644
--- a/tests/data_files/ec_pub.comp.pem
+++ b/tests/data_files/ec_pub.comp.pem
@@ -1,4 +1,4 @@
 -----BEGIN PUBLIC KEY-----
-MDEwEwYHKoZIzj0CAQYIKoZIzj0DAQEDGgACvHl9s65/COw9SWtPtBGz9iClWKUB
-4CIt
+MDEwEwYHKoZIzj0CAQYIKoZIzj0DAQEDGgADUXW83zCjcPOdU5PmEnKI2AFntfS0
+t3bG
 -----END PUBLIC KEY-----