ASoC: SOF: Intel: hda: Place check before dereference

ASoC: SOF: Intel: hda: Place check before dereference

The struct hext_stream is dereferenced before it is checked for NULL.
Although it can never be NULL due to a check prior to
hda_dsp_iccmax_stream_hw_params() being called, this change clears any
confusion regarding hext_stream possibly being NULL.

Check hext_stream for NULL and then assign its members.

Detected by Smatch:
sound/soc/sof/intel/hda-stream.c:488 hda_dsp_iccmax_stream_hw_params() warn:
variable dereferenced before check 'hext_stream' (see line 486)

Fixes: aca961f196e5d ("ASoC: SOF: Intel: hda: Add helper function to program ICCMAX stream")
Signed-off-by: Ethan Tidmore <ethantidmore06@gmail.com>
Link: https://patch.msgid.link/20260324173830.17563-1-ethantidmore06@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>