Change in coreboot[master]: soc/intel/common/block/pcie/rtd3: Add PM methods to the device.

[Cliff Huang (Code Review)]

Attention is currently required from: Lance Zhao, Anil Kumar K, Selma Bensaid, Tim Wawrzynczak, Paul Menzel, Thejaswani Putta, Patrick Rudolph.
Cliff Huang has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/61352 )

Change subject: soc/intel/common/block/pcie/rtd3: Add PM methods to the device.
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Patch Set 5:

(1 comment)

File src/soc/intel/common/block/pcie/rtd3/chip.h:

https://review.coreboot.org/c/coreboot/+/61352/comment/9140d373_65890f7f 
PS1, Line 53: ext_pm_support
> Done

Tim, ex_pm_support has been changed to use 'enum' type. 
- enum type is added in the chip.h 
- ex_pm_support is also checked if the methods to request are available or not.
- rtd3 device is also referenced to get its config for this field in the device.
- device calls the exported methods based on ex_pm_support enum.
Please also see the other reviews:
  https://review.coreboot.org/c/coreboot/+/61354 
  https://review.coreboot.org/c/coreboot/+/61355