Change in coreboot[master]: cpu/x86/smm: Add weak SoC and mainboard init and exit methods

[Karthik Ramasubramanian (Code Review)]

Attention is currently required from: Raul Rangel, Martin Roth, Felix Held.
Karthik Ramasubramanian has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/62500 )

Change subject: cpu/x86/smm: Add weak SoC and mainboard init and exit methods
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Patch Set 3:

(2 comments)

File src/include/cpu/x86/smm.h:

https://review.coreboot.org/c/coreboot/+/62500/comment/50b97542_7c6d095e 
PS3, Line 54: early
Any relevance to add early?

https://review.coreboot.org/c/coreboot/+/62500/comment/862a90e1_64cb1a3b 
PS3, Line 55: void smm_mainboard_early_init(void);
            : void smm_mainboard_exit(void);
In the subsequent patchset, we use only SoC hooks. Shall the mainboard hooks be added when it is needed?