Change in coreboot[master]: soc/intel/common/cse: Add `cse_send_end_of_post()` a public function

[Angel Pons (Code Review)]

Attention is currently required from: Subrata Banik, Tim Wawrzynczak, Nick Vaccaro, Werner Zeh, Patrick Rudolph, EricR Lai.
Angel Pons has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/61519 )

Change subject: soc/intel/common/cse: Add `cse_send_end_of_post()` a public function
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Patch Set 4:

(1 comment)

File src/soc/intel/common/block/cse/cse_eop.c:

https://review.coreboot.org/c/coreboot/+/61519/comment/fa7d3cce_58653ae4 
PS4, Line 199: 
             : 	if (eop_sent) {
             : 		printk(BIOS_ERR, "EOP already sent\n");
             : 		return;
             : 	}
             :
> IMO, we should check for HW mechanism, asked Intel for sharing some insights. […]

I suggested adding this as there was a TODO comment, and I thought this would be better than nothing. However, if there's something better, let's use it instead.