[M] Change in coreboot[main]: libpayload: Unify selfboot() implementations

[Julius Werner (Code Review)]

Attention is currently required from: Stephen Boyd, Subrata Banik, Yu-Ping Wu.

Julius Werner has posted comments on this change by Julius Werner. ( https://review.coreboot.org/c/coreboot/+/86142?usp=email )

Change subject: libpayload: Unify selfboot() implementations
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Patch Set 1:

(1 comment)

File payloads/libpayload/libc/selfboot.c:

https://review.coreboot.org/c/coreboot/+/86142/comment/fbba02a0_e8231ae9?usp... :
PS1, Line 35: 	__attribute__((__regparm__(0)))
I think technically this doesn't really do anything, because our default calling convention is already `regparm(0)` to begin with. But coreboot also still does it when loading the payload, so I guess it's more consistent to do it here too.