spi: don't unoptimize message in spi_async()

In the Linux kernel, the following vulnerability has been resolved: spi: don't unoptimize message in spi_async() Calling spi_maybe_unoptimize_message() in spi_async() is wrong because the message is likely to be in the queue and not transferred yet. This can corrupt the message while it is being used by the controller driver. spi_maybe_unoptimize_message() is already called in the correct place in spi_finalize_current_message() to balance the call to spi_maybe_optimize_message() in spi_async().