Remove message size checks for RSA and DSA signing operations.

There appears to be too much code, both production and tests, that
assumes it can feed various-sized messages to signing ops.  This change
essentially just falls back on openssl, letting it decide what is
acceptable and what is not.  That should make it bug-compatible with
softkeymaster, and perhaps with other TEE implementations.

Change-Id: I6185fdef3abf19321029d0b192669b722b363cf8
diff --git a/google_keymaster_test.cpp b/google_keymaster_test.cpp
index a492743..18befde 100644
--- a/google_keymaster_test.cpp
+++ b/google_keymaster_test.cpp
@@ -657,7 +657,7 @@
     finish_request.op_handle = begin_response.op_handle;
     FinishOperationResponse finish_response;
     device.FinishOperation(finish_request, &finish_response);
-    ASSERT_EQ(KM_ERROR_INVALID_INPUT_LENGTH, finish_response.error);
+    ASSERT_EQ(KM_ERROR_UNKNOWN_ERROR, finish_response.error);
     EXPECT_EQ(0U, finish_response.output.available_read());
 
     EXPECT_EQ(KM_ERROR_INVALID_OPERATION_HANDLE, device.AbortOperation(begin_response.op_handle));