Change in coreboot[master]: mb/google/brya: Add companion device name to WWAN PCIe generic device

[Tim Wawrzynczak (Code Review)]

Attention is currently required from: Bora Guvendik, Cliff Huang, Selma Bensaid.
Tim Wawrzynczak has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/62330 )

Change subject: mb/google/brya: Add companion device name to WWAN PCIe generic device
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Patch Set 10:

(1 comment)

File src/mainboard/google/brya/variants/brya0/overridetree.cb:

https://review.coreboot.org/c/coreboot/+/62330/comment/1b4ecdda_9e54f914 
PS10, Line 213: rp6_wwan
> do you mean that PCI generic is no need at all in the device tree since wwan provides _DSD? we can r […]

We are supposed to have the DmaProperty in 3 places total:

1) CNVi device - https://review.coreboot.org/c/coreboot/+/61385
2) WWAN device (PXSX) - https://review.coreboot.org/c/coreboot/+/62436/4
3) PCIe RP of the WWAN device (_SB.PCI0.RP06) - what this is one is supposed to be doing

actually is the companion device even necessary? did I just get myself all tangled up in ACPI devices?