ASoC: amd: acp70: add standalone RT721 SoundWire machine

ASoC: amd: acp70: add standalone RT721 SoundWire machine

The ASUS Vivobook 18 M1807GA (AMD ACP7.x, PCI 1022:15e2, subsystem
1043:3531) exposes a single Realtek RT721 SDCA codec on SoundWire link 1.
The BIOS reports the ACP audio config flag as 0 (SoundWire mode), so
snd_pci_ps claims the device, brings up the SoundWire managers and
enumerates the RT721 peripheral (sdw:0:1:025d:0721:01); the rt721-sdca
codec driver binds successfully.

No sound card is created, however: acp63_sdw_machine_select() walks
snd_soc_acpi_amd_acp70_sdw_machines[] and finds no entry whose declared
SoundWire peripherals are all present on the bus. The only existing RT721
entry, acp70_rt721_l1u0_tas2783x2_l1u8b, additionally requires two
TAS2783 amplifiers and deliberately exposes the RT721 as jack + DMIC
only. This M1807GA variant has no external amplifiers - the RT721's
internal AIF2 amplifier path drives the speakers - so that entry never
matches and no machine device is registered.

Add a standalone RT721 machine entry for link 1 exposing all three RT721
endpoints (jack/AIF1, speaker amplifier/AIF2, DMIC/AIF3), mirroring the
standalone RT722 configuration. Place it after the TAS2783 combo entry so
platforms that do have the external amplifiers continue to match the more
specific entry first.

ACPI _ADR of the codec: 0x000130025D072101
(link_id=1 version=3 mfg_id=0x025d Realtek part_id=0x0721 class=0x01).

Verified on the hardware: with the entry present the amd_sdw machine
binds, an "amd-soundwire" card is registered exposing the rt721-sdca
AIF1 (SimpleJack) and AIF2 (SmartAmp) PCM devices, and audio plays out
of the built-in speakers.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=221282
Signed-off-by: Aleksander Pshenitsyn <brains.fatman@gmail.com>
Link: https://patch.msgid.link/20260531101159.14241-1-brains.fatman@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>