Tools: hv: Handle the case when the target file exists correctly

Return the appropriate error code and handle the case when the target
file exists correctly. This fixes a bug.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Cc: <stable@vger.kernel.org> [3.14]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>