Remove `mbedtls_rsa_check_crt`

This is no longer needed after the decision to not exhaustively validate private key material.
diff --git a/library/pkparse.c b/library/pkparse.c
index a6916e7..f0b9db3 100644
--- a/library/pkparse.c
+++ b/library/pkparse.c
@@ -751,8 +751,7 @@
     /* Check optional parameters */
     if( ( ret = mbedtls_asn1_get_mpi( &p, end, &DP ) ) != 0 ||
         ( ret = mbedtls_asn1_get_mpi( &p, end, &DQ ) ) != 0 ||
-        ( ret = mbedtls_asn1_get_mpi( &p, end, &QP ) ) != 0 ||
-        ( ret = mbedtls_rsa_check_crt( rsa, &DP, &DQ, &QP ) ) != 0 )
+        ( ret = mbedtls_asn1_get_mpi( &p, end, &QP ) ) != 0 )
         goto cleanup;
 
     if( p != end )