ASoC: amd: acp: Fix return value check in acp_machine_select()

ASoC: amd: acp: Fix return value check in acp_machine_select()

In case of error, platform_device_register_data() returns ERR_PTR()
and never returns NULL. The NULL test in the return value check
should be replaced with IS_ERR().

Reported-by: Hulk Robot <hulkci@huawei.com>
Fixes: e646b51f5dd5 ("ASoC: amd: acp: Add callback for machine driver on ACP")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Link: https://lore.kernel.org/r/20211027065228.833825-1-yangyingliang@huawei.com
Signed-off-by: Mark Brown <broonie@kernel.org>