Change in coreboot[master]: intel/block/cpu: Keep flash region cached until the payload is loaded

[Werner Zeh (Code Review)]

Attention is currently required from: Arthur Heymans, Patrick Georgi, Subrata Banik, Maulik V Vaghela, Rizwan Qureshi, Sridhar Siricilla, Angel Pons, Patrick Rudolph.
Werner Zeh has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/62566 )

Change subject: intel/block/cpu: Keep flash region cached until the payload is loaded
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Patch Set 2:

(1 comment)

Patchset:

PS2: 
I made some further tests today. It seems like my bad payload loading time (12 sec) is caused by TPM_MEASURED_BOOT. Once I disable it the normal loading time (meaning without this patch) is reduced to 3.5 sec. Though, with this patch I can speed it up to 2.1 sec (so now we still have an influence but now in the expected magnitude).
I will have a closer look to why measuring is slowing it down so bad, my first guess would be the small cache of 1.5 MB on EHL.