ASoC: SOF: Replace zero-length array with flexible-array member

ASoC: SOF: Replace zero-length array with flexible-array member

There is a regular need in the kernel to provide a way to declare having
a dynamically sized set of trailing elements in a structure. Kernel code
should always use "flexible array members"[1] for these cases. The older
style of one-element or zero-length arrays should no longer be used[2].

This helps with the ongoing efforts to globally enable -Warray-bounds
and get us closer to being able to tighten the FORTIFY_SOURCE routines
on memcpy().

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays

Link: https://github.com/KSPP/linux/issues/78
Link: https://github.com/KSPP/linux/issues/180
Suggested-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Stephen Kitt <steve@sk2.org>
Acked-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20220217132755.1786130-1-steve@sk2.org
Signed-off-by: Mark Brown <broonie@kernel.org>