ASoC: Intel: Atom: add a missing star in a memcpy call

In sst_prepare_and_post_msg(), when a response is received in "block",
the following code gets executed:

    *data = kzalloc(block->size, GFP_KERNEL);
    memcpy(data, (void *) block->data, block->size);

The memcpy() call overwrites the content of the *data pointer instead of
filling the newly-allocated memory (which pointer is hold by *data).
Fix this by merging kzalloc+memcpy into a single kmemdup() call.

Thanks Joe Perches for suggesting using kmemdup()

Fixes: 60dc8dba

 ("ASoC: Intel: sst: Add some helper functions")
Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org