[L] Change in coreboot[master]: mb/intel/mtlrvp: Enable EC and building ChromeOS

[Harsha B R (Code Review)]

Attention is currently required from: Wonkyu Kim, Ravishankar Sarawadi, Rizwan Qureshi, Paul Menzel, Angel Pons, Krishna P Bhat D, Tim Wawrzynczak, Tarun Tuli, Jamie Ryu, Subrata Banik, Kapil Porwal, Nick Vaccaro, Ronak Kanabar, Usha P, Raj Astekar.

Harsha B R has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/66101 )

Change subject: mb/intel/mtlrvp: Enable EC and building ChromeOS
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Patch Set 10:

(1 comment)

File src/mainboard/intel/mtlrvp/Kconfig:

https://review.coreboot.org/c/coreboot/+/66101/comment/a2ee3419_0de698c9 
PS4, Line 45: 	default MTL_EC_DETECT
> I tried the override from config file, the config override works as intended and choose the EC confi […]

Current patch defaults the On-board EC to MTL_CHROME_EC (though having the option to config to MTL_INTEL_EC through Kconfig). Created CL (CB:70020) to resolve the on-board EC selection.