pkcs7: Fix dependencies for pkcs7 tests

Fixes include removing PEM dependency for greater
coverage when PEM config is not set and defining
test dependencies at the appropriate level.

Signed-off-by: Nick Child <nick.child@ibm.com>
diff --git a/tests/data_files/Makefile b/tests/data_files/Makefile
index 8c7520f..b92944a 100644
--- a/tests/data_files/Makefile
+++ b/tests/data_files/Makefile
@@ -1147,6 +1147,15 @@
 	cat pkcs7-rsa-sha256-2.crt pkcs7-rsa-sha256-2.key > pkcs7-rsa-sha256-2.pem
 all_final += pkcs7-rsa-sha256-2.crt
 
+# Convert signing certs to DER for testing PEM-free builds
+pkcs7-rsa-sha256-1.der: $(pkcs7_test_cert_1)
+	$(OPENSSL) x509 -in pkcs7-rsa-sha256-1.crt -out $@ -outform DER
+all_final += pkcs7-rsa-sha256-1.der
+
+pkcs7-rsa-sha256-2.der: $(pkcs7_test_cert_2)
+	$(OPENSSL) x509 -in pkcs7-rsa-sha256-2.crt -out $@ -outform DER
+all_final += pkcs7-rsa-sha256-2.der
+
 # pkcs7 signature file with CERT
 pkcs7_data_cert_signed_sha256.der: $(pkcs7_test_file) $(pkcs7_test_cert_1)
 	$(OPENSSL) smime -sign -binary -in pkcs7_data.bin -out $@ -md sha256 -signer pkcs7-rsa-sha256-1.pem -noattr -outform DER -out $@