check_files.py: Exempt only everest from license checking

Signed-off-by: Ronald Cron <ronald.cron@arm.com>
diff --git a/tests/scripts/check_files.py b/tests/scripts/check_files.py
index 8c7c2a6..e937202 100755
--- a/tests/scripts/check_files.py
+++ b/tests/scripts/check_files.py
@@ -368,9 +368,8 @@
     heading = "License issue:"
 
     LICENSE_EXEMPTION_RE_LIST = [
-        # Third-party code, other than whitelisted third-party modules,
-        # may be under a different license.
-        r'tf-psa-crypto/drivers/(?!(builtin|p256-m)/.*)',
+        # Exempt third-party drivers which may be under a different license
+        r'tf-psa-crypto/drivers/(?=(everest)/.*)',
         # Documentation explaining the license may have accidental
         # false positives.
         r'(ChangeLog|LICENSE|framework\/LICENSE|[-0-9A-Z_a-z]+\.md)\Z',