public_key: move common functions to public key helper

Move public_key_free and public_key_signature_free as helper
functions that can be shared by legacy crypto lib and MbedTLS
implementation.

Signed-off-by: Raymond Mao <raymond.mao@linaro.org>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
diff --git a/lib/crypto/Makefile b/lib/crypto/Makefile
index bec1bc9..4ad1849 100644
--- a/lib/crypto/Makefile
+++ b/lib/crypto/Makefile
@@ -7,7 +7,9 @@
 
 asymmetric_keys-y := asymmetric_type.o
 
-obj-$(CONFIG_$(SPL_)ASYMMETRIC_PUBLIC_KEY_SUBTYPE) += public_key.o
+obj-$(CONFIG_$(SPL_)ASYMMETRIC_PUBLIC_KEY_SUBTYPE) += \
+	public_key_helper.o \
+	public_key.o
 
 #
 # RSA public key parser
diff --git a/lib/crypto/public_key.c b/lib/crypto/public_key.c
index 6efe951..4087429 100644
--- a/lib/crypto/public_key.c
+++ b/lib/crypto/public_key.c
@@ -51,38 +51,7 @@
 }
 #endif
 
-/*
- * Destroy a public key algorithm key.
- */
-void public_key_free(struct public_key *key)
-{
-	if (key) {
-		kfree(key->key);
-		kfree(key->params);
-		kfree(key);
-	}
-}
-EXPORT_SYMBOL_GPL(public_key_free);
-
 #ifdef __UBOOT__
-/*
- * from <linux>/crypto/asymmetric_keys/signature.c
- *
- * Destroy a public key signature.
- */
-void public_key_signature_free(struct public_key_signature *sig)
-{
-	int i;
-
-	if (sig) {
-		for (i = 0; i < ARRAY_SIZE(sig->auth_ids); i++)
-			free(sig->auth_ids[i]);
-		free(sig->s);
-		free(sig->digest);
-		free(sig);
-	}
-}
-EXPORT_SYMBOL_GPL(public_key_signature_free);
 
 /**
  * public_key_verify_signature - Verify a signature using a public key.
diff --git a/lib/crypto/public_key_helper.c b/lib/crypto/public_key_helper.c
new file mode 100644
index 0000000..2c55922
--- /dev/null
+++ b/lib/crypto/public_key_helper.c
@@ -0,0 +1,39 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * X509 helper functions
+ *
+ * Copyright (c) 2012 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+#include <linux/compat.h>
+#include <crypto/public_key.h>
+
+/*
+ * Destroy a public key algorithm key.
+ */
+void public_key_free(struct public_key *key)
+{
+	if (key) {
+		kfree(key->key);
+		kfree(key->params);
+		kfree(key);
+	}
+}
+
+/*
+ * from <linux>/crypto/asymmetric_keys/signature.c
+ *
+ * Destroy a public key signature.
+ */
+void public_key_signature_free(struct public_key_signature *sig)
+{
+	int i;
+
+	if (sig) {
+		for (i = 0; i < ARRAY_SIZE(sig->auth_ids); i++)
+			kfree(sig->auth_ids[i]);
+		kfree(sig->s);
+		kfree(sig->digest);
+		kfree(sig);
+	}
+}