Modifies typedef of mbedtls_pk_rsa_alt_sign_func

This commit modifies the typedef of
mbedtls_pk_rsa_alt_sign_func and propagates the
associated changes throughout the codebase.

Signed-off-by: Thomas Daubney <thomas.daubney@arm.com>
diff --git a/library/pk_wrap.c b/library/pk_wrap.c
index e1ad507..ec07c60 100644
--- a/library/pk_wrap.c
+++ b/library/pk_wrap.c
@@ -770,7 +770,7 @@
     if( *sig_len > MBEDTLS_PK_SIGNATURE_MAX_SIZE )
         return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );
 
-    return( rsa_alt->sign_func( rsa_alt->key, f_rng, p_rng, MBEDTLS_RSA_PRIVATE,
+    return( rsa_alt->sign_func( rsa_alt->key, f_rng, p_rng,
                 md_alg, (unsigned int) hash_len, hash, sig ) );
 }