ASoC: Intel: soc-acpi: Fix missing empty terminators

Merge series from Bard Liao <yung-chuan.liao@linux.intel.com>:

There is no links_num in struct snd_soc_acpi_mach {}, and we test
!link->num_adr as a condition to end the loop in hda_sdw_machine_select().
So an empty item in struct snd_soc_acpi_link_adr array is required.