Change in coreboot[master]: soc/intel: Move `pmc_clear_pmcon_sts()` into IA common code

[Michael Niewöhner (Code Review)]

Attention is currently required from: Felix Singer, Jeff Daly, Mariusz Szafrański, Jonathan Zhang, Arthur Heymans, Andrey Petrov, Patrick Rudolph, Nico Huber, Anjaneya "Reddy" Chagam, Subrata Banik, Johnny Lin, Tim Wawrzynczak, Suresh Bellampalli, Christian Walter, Vanessa Eusebio, Lean Sheng Tan, Michal Motyl, Werner Zeh, Tim Chu.
Michael Niewöhner has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/62064 )

Change subject: soc/intel: Move `pmc_clear_pmcon_sts()` into IA common code
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Patch Set 12:

(4 comments)

File src/soc/intel/common/block/pmc/Kconfig:

https://review.coreboot.org/c/coreboot/+/62064/comment/6742ca39_01a44ea8 
PS12, Line 13: GEN_PMCON_A
At least drop the _A, since both _A and _B were moved.

Actually, all PMC registers were moved:
- GEN_PMCON_A/B
- ETR3
- SCIS
- BM_CX_CNF

So, maybe we can find a better name? Not a must, though.

File src/soc/intel/common/block/pmc/pmclib.c:

https://review.coreboot.org/c/coreboot/+/62064/comment/9abf9f93_56cb44b1 
PS12, Line 614: 	 *    And, the PMC device is visible over the PCI bus, so the SoC user selects
              : 	 *    `SOC_INTEL_COMMON_BLOCK_PMC_DISCOVERABLE` Kconfig.
              : 
with the new Kconfig this doesn't matter anymore, does it?

https://review.coreboot.org/c/coreboot/+/62064/comment/f193356f_bf572a05 
PS12, Line 617: 	 *    And, the PMC device is not over the PCI bus and hidden by the FSP.
same as 617

https://review.coreboot.org/c/coreboot/+/62064/comment/fad12059_f966b182 
PS12, Line 619: 	 * Using SOC_INTEL_MEM_MAPPED_GEN_PMCON_A Kconfig to perform GEN_PMCON_A register
              : 	 * programming.
              : 
doesn't provide any additional information, does ot?