RSA: Use hashlen as the hash input size as documented

Where hashlen was previously ignored when the hash length could be
inferred from an md_alg parameter, the two must now match.

Adapt the existing tests accordingly. Adapt the sample programs accordingly.

This commit does not add any negative testing.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/programs/pkey/rsa_verify.c b/programs/pkey/rsa_verify.c
index fff568a..5a68246 100644
--- a/programs/pkey/rsa_verify.c
+++ b/programs/pkey/rsa_verify.c
@@ -141,7 +141,7 @@
     }
 
     if( ( ret = mbedtls_rsa_pkcs1_verify( &rsa, MBEDTLS_MD_SHA256,
-                                          20, hash, buf ) ) != 0 )
+                                          32, hash, buf ) ) != 0 )
     {
         mbedtls_printf( " failed\n  ! mbedtls_rsa_pkcs1_verify returned -0x%0x\n\n", (unsigned int) -ret );
         goto exit;