[NUC472/M487] Fix context clone corner case in SHA alter.

As destination/source contexts are the same, we return immediately.

features/mbedtls/targets/TARGET_NUVOTON/TARGET_M480/sha/sha1_alt.c

@@ -63,6 +63,11 @@ void mbedtls_sha1_free(mbedtls_sha1_context *ctx)
 void mbedtls_sha1_clone(mbedtls_sha1_context *dst,
                         const mbedtls_sha1_context *src)
 {
+    // Corner case: Destination/source contexts are the same
+    if (dst == src) {
+        return;
+    }
+
     // If dst is H/W context, we need to change it to S/W context first before cloning to.
     if (dst->active_ctx == &dst->hw_ctx) {
         mbedtls_sha1_free(dst);

features/mbedtls/targets/TARGET_NUVOTON/TARGET_M480/sha/sha256_alt.c

@@ -63,6 +63,11 @@ void mbedtls_sha256_free(mbedtls_sha256_context *ctx)
 void mbedtls_sha256_clone(mbedtls_sha256_context *dst,
                           const mbedtls_sha256_context *src)
 {
+    // Corner case: Destination/source contexts are the same
+    if (dst == src) {
+        return;
+    }
+
     // If dst is H/W context, we need to change it to S/W context first before cloning to.
     if (dst->active_ctx == &dst->hw_ctx) {
         mbedtls_sha256_free(dst);

features/mbedtls/targets/TARGET_NUVOTON/TARGET_M480/sha/sha512_alt.c

@@ -63,6 +63,11 @@ void mbedtls_sha512_free(mbedtls_sha512_context *ctx)
 void mbedtls_sha512_clone(mbedtls_sha512_context *dst,
                           const mbedtls_sha512_context *src)
 {
+    // Corner case: Destination/source contexts are the same
+    if (dst == src) {
+        return;
+    }
+
     // If dst is H/W context, we need to change it to S/W context first before cloning to.
     if (dst->active_ctx == &dst->hw_ctx) {
         mbedtls_sha512_free(dst);

features/mbedtls/targets/TARGET_NUVOTON/TARGET_NUC472/sha/sha1_alt.c

@@ -63,6 +63,11 @@ void mbedtls_sha1_free(mbedtls_sha1_context *ctx)
 void mbedtls_sha1_clone(mbedtls_sha1_context *dst,
                         const mbedtls_sha1_context *src)
 {
+    // Corner case: Destination/source contexts are the same
+    if (dst == src) {
+        return;
+    }
+
     // If dst is H/W context, we need to change it to S/W context first before cloning to.
     if (dst->active_ctx == &dst->hw_ctx) {
         mbedtls_sha1_free(dst);

features/mbedtls/targets/TARGET_NUVOTON/TARGET_NUC472/sha/sha256_alt.c

@@ -63,6 +63,11 @@ void mbedtls_sha256_free(mbedtls_sha256_context *ctx)
 void mbedtls_sha256_clone(mbedtls_sha256_context *dst,
                           const mbedtls_sha256_context *src)
 {
+    // Corner case: Destination/source contexts are the same
+    if (dst == src) {
+        return;
+    }
+
     // If dst is H/W context, we need to change it to S/W context first before cloning to.
     if (dst->active_ctx == &dst->hw_ctx) {
         mbedtls_sha256_free(dst);