Rm mbedtls_ prefix form static functions

- prefix is no necessary for static ids and makes lines longer
- most often omitted (even though we're not fully consistent)
diff --git a/library/chachapoly.c b/library/chachapoly.c
index 5ce27f2..d0c3551 100644
--- a/library/chachapoly.c
+++ b/library/chachapoly.c
@@ -54,7 +54,7 @@
  *
  * \param ctx       The ChaCha20-Poly1305 context.
  */
-static void mbedtls_chachapoly_pad_aad( mbedtls_chachapoly_context *ctx )
+static void chachapoly_pad_aad( mbedtls_chachapoly_context *ctx )
 {
     uint32_t partial_block_len = (uint32_t) ( ctx->aad_len % 16U );
     unsigned char zeroes[15];
@@ -73,7 +73,7 @@
  *
  * \param ctx       The ChaCha20-Poly1305 context.
  */
-static void mbedtls_chachapoly_pad_ciphertext( mbedtls_chachapoly_context *ctx )
+static void chachapoly_pad_ciphertext( mbedtls_chachapoly_context *ctx )
 {
     uint32_t partial_block_len = (uint32_t) ( ctx->ciphertext_len % 16U );
     unsigned char zeroes[15];
@@ -218,7 +218,7 @@
     {
         ctx->state = CHACHAPOLY_STATE_CIPHERTEXT;
 
-        mbedtls_chachapoly_pad_aad( ctx );
+        chachapoly_pad_aad( ctx );
     }
 
     ctx->ciphertext_len += len;
@@ -257,11 +257,11 @@
 
     if ( ctx->state == CHACHAPOLY_STATE_AAD )
     {
-        mbedtls_chachapoly_pad_aad( ctx );
+        chachapoly_pad_aad( ctx );
     }
     else if ( ctx->state == CHACHAPOLY_STATE_CIPHERTEXT )
     {
-        mbedtls_chachapoly_pad_ciphertext( ctx );
+        chachapoly_pad_ciphertext( ctx );
     }
 
     ctx->state = CHACHAPOLY_STATE_FINISHED;