Change in coreboot[master]: lillupup: provide additional VBT for lillipup OLED sku

[Tim Wawrzynczak (Code Review)]

Attention is currently required from: Kevin Chang, Nick Vaccaro, YH Lin, Zhuohao Lee.
Tim Wawrzynczak has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/52150 )

Change subject: lillupup: provide additional VBT for lillipup OLED sku
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Patch Set 2:

(1 comment)

Patchset:

PS2: 
This line: https://review.coreboot.org/plugins/gitiles/coreboot/+/refs/heads/master/src...

should be changed in this patchset to be just:
```
ramstage-y += variant.c
```

along with changing get_wifi_sar_cbfs_filename to:
```
const char *get_wifi_sar_cbfs_filename(void)
{
        if (CONFIG(FW_CONFIG)) {
        	if (fw_config_probe(FW_CONFIG(WIFI_SAR_ID, WIFI_SAR_ID_0)))
        		return "wifi_sar_0.hex";
        	else if (fw_config_probe(FW_CONFIG(WIFI_SAR_ID, WIFI_SAR_ID_1)))
        		return "wifi_sar_1.hex";
        }

return WIFI_SAR_CBFS_DEFAULT_FILENAME;
}
```

because variant.c doesn't always depend on fw_config anymore