ASoC: soc-ops-test: dynamically allocate struct snd_ctl_elem_value

ASoC: soc-ops-test: dynamically allocate struct snd_ctl_elem_value

This structure is really too larget to be allocated on the stack:

	linux/sound/soc/soc-ops-test.c:520:1: error: the frame size of\
	1304 bytes is larger than 1280 bytes
	[-Werror=frame-larger-than=]

Change the function to dynamically allocate it instead.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://patch.msgid.link/87sek489l8.wl-kuninori.morimoto.gx@renesas.com
Signed-off-by: Mark Brown <broonie@kernel.org>