ASoC: tegra: Fix -Wuninitialized in tegra210_amx_platform_probe()

ASoC: tegra: Fix -Wuninitialized in tegra210_amx_platform_probe()

Clang warns (or errors with CONFIG_WERROR=y):

  sound/soc/tegra/tegra210_amx.c:553:10: error: variable 'soc_data' is uninitialized when used here [-Werror,-Wuninitialized]
    553 |                                             soc_data->regmap_conf);
        |                                             ^~~~~~~~

A refactoring removed the initialization of this variable but its use
was not updated. Use the soc_data value in the amx variable to resolve
the warning and remove the soc_data variable, as it is now entirely
unused.

Closes: https://github.com/ClangBuiltLinux/linux/issues/1943
Fixes: 9958d85968ed ("ASoC: Use device_get_match_data()")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20231011-asoc-tegra-fix-uninit-soc_data-v1-1-0ef0ab44cf48@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>