Change in coreboot[master]: ec/google/chromeec: Provide EC access for Retimer firmware update

[John Zhao (Code Review)]

Attention is currently required from: Tim Wawrzynczak, Duncan Laurie, John Zhao, Brandon Breitenstein, Rajmohan Mani.
John Zhao has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/49257 )

Change subject: ec/google/chromeec: Provide EC access for Retimer firmware update
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Patch Set 5:

(1 comment)

File src/ec/google/chromeec/ec_acpi.c:

https://review.coreboot.org/c/coreboot/+/49257/comment/1424a6a6_eabcc3f0 
PS4, Line 242: \_SB_.PCI0.LPCB.EC0_.
> You have an extra pnp 0c09 device, that might prevent the alias from taking effect?, e.g.: […]

Got it. The desired path is _SB.PCI0.LPCB.EC0.RFWU. But the chromeec has path _SB.PCI0.LPCB.EC0.CREC which would present the wrongly _SB.PCI0.LPCB.EC0.CREC.RFWU due to the extra CREC if with  acpi_device_path_join(ec_dev, "RWFU"). Any suggestion?