Fix lint issues

Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>

scripts/mbedtls_dev/ecp_common.py

@@ -17,5 +17,6 @@
 from . import bignum_common
 
 class EcpOperationCommon(bignum_common.ModOperationCommon):
+    #pylint: disable=abstract-method
     """Target for ecp test case generation."""
     pass

tests/scripts/generate_ecp_tests.py

@@ -57,7 +57,7 @@ import sys
 
 import scripts_path # pylint: disable=unused-import
 from mbedtls_dev import test_data_generation
-from mbedtls_dev import ecp_common
+
 # Import modules containing additional test classes
 # Test function classes in these modules will be registered by
 # the framework