Pylint: minor code simplifications

Simplify the code in minor ways. Each of this changes fixes a warning
from Pylint 2.4 that doesn't appear with Pylint 1.7.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/scripts/mbedtls_test.py b/tests/scripts/mbedtls_test.py
index 9a58a36..709bb1a 100755
--- a/tests/scripts/mbedtls_test.py
+++ b/tests/scripts/mbedtls_test.py
@@ -262,7 +262,7 @@
             data_bytes += bytearray(dependencies)
         data_bytes += bytearray([function_id, len(parameters)])
         for typ, param in parameters:
-            if typ == 'int' or typ == 'exp':
+            if typ in ('int', 'exp'):
                 i = int(param, 0)
                 data_bytes += b'I' if typ == 'int' else b'E'
                 self.align_32bit(data_bytes)