[coreboot-gerrit] [S] Change in coreboot[master]: mb/google/myst: Add smihandler

[Tim Van Patten (Code Review)]

Attention is currently required from: Raul Rangel, Jon Murphy, Eric Lai, Karthik Ramasubramanian, Mark Hasemeyer.

Tim Van Patten has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/74100 )

Change subject: mb/google/myst: Add smihandler
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Patch Set 6:

(2 comments)

File src/mainboard/google/myst/variants/baseboard/Makefile.inc:

https://review.coreboot.org/c/coreboot/+/74100/comment/34299d75_da9c9ff9 
PS6, Line 5: smm-y += gpio.c
Missing `smihandler.c`.

File src/mainboard/google/myst/variants/baseboard/smihandler.c:

https://review.coreboot.org/c/coreboot/+/74100/comment/2f19805e_4a5c60ee 
PS6, Line 10: void mainboard_smi_sleep(u8 slp_typ)
Missing these calls from Skyrim:

```
    variant_sleep_gpio_table(&gpios, &num_gpios);
    gpio_configure_pads(gpios, num_gpios);
```

Is that work done somewhere else, or unnecessary?