ASoC: Intel: Skylake: fix typo in sizeof

ASoC: Intel: Skylake: fix typo in sizeof

The size of the pointer to a data structure to send is erroneously
passed to sst_ipc_tx_message_wait() as its tx_bytes argument. It should
be given the size of the pointed skl_ipc_dxstate_info structure instead.

Coincidentally, both the pointer and the structure have the same size of
8 bytes on a 64 bit machine, which "masks" the issue. Compiling for 32
bit reveals the issue more clearly.

Fix the typo for correctness, and to make the code robust to future
evolutions of the skl_ipc_dxstate_info structure size.

This fixes the following coccicheck error:

  sound/soc/intel/skylake/skl-sst-ipc.c:641:8-14: ERROR: application of sizeof to pointer

Signed-off-by: Vincent Stehlé <vincent.stehle@laposte.net>
Cc: Subhransu S. Prusty <subhransu.s.prusty@intel.com>
Cc: Jeeja KP <jeeja.kp@intel.com>
Cc: Vinod Koul <vinod.koul@intel.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: trivial@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>