Change in coreboot[master]: mb/google/volteer:intel/common/block: Move mainboard api to tcss comm...

[Tim Wawrzynczak (Code Review)]

Attention is currently required from: Furquan Shaikh, Paul Menzel, Sridhar Siricilla, Deepti Deshatty, Patrick Rudolph.
Tim Wawrzynczak has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/54733 )

Change subject: mb/google/volteer:intel/common/block: Move mainboard api to tcss common block
......................................................................

Patch Set 5:

(3 comments)

File src/soc/intel/common/block/tcss/tcss.c:

https://review.coreboot.org/c/coreboot/+/54733/comment/bebbfd8d_03b81bf4 
PS5, Line 342: const struct device *get_pmc_mux(void)
             : {
             : 	const struct device *pmc;
             : 	const struct device *mux;
             : 
             : 	pmc = pcidev_path_on_root(PCH_DEVFN_PMC);
             : 	if (!pmc || !pmc->link_list) {
             : 		printk(BIOS_ERR, "%s: unable to find PMC device or its mux\n", __func__);
             : 		return NULL;
             : 	}
             : 
             : 	mux = pmc->link_list->children;
             : 	return mux;
             : }
This function isn't required, it can be rolled up into the call to `find_dev_nested_path` below

https://review.coreboot.org/c/coreboot/+/54733/comment/e1ce582a_9f8227e5 
PS5, Line 361: 
             : 	const struct device *mux = get_pmc_mux();
             : 
             : 	if (!mux || !mux->link_list) {
             : 		printk(BIOS_ERR, "%s: unable to find PMC mux device or its connector\n",
             : 				__func__);
             : 		return NULL;
             : 	}
same as above, this won't be required

https://review.coreboot.org/c/coreboot/+/54733/comment/892e5e25_8eb3ca25 
PS5, Line 372: 		const struct device_path conn_path[] = {
             : 			{.type = DEVICE_PATH_GENERIC, .generic.id = port, .generic.subid = 0},
             : 		};
             : 		const struct device *conn = find_dev_nested_path(mux->link_list, conn_path,
             : 								ARRAY_SIZE(conn_path));
You can get rid of the two above sections and just add the PMC device into this list here:
```
const struct device_path conn_path[] = {
        {.type = DEVICE_PATH_PCI, .pci.devfn = PCH_DEVFN_PMC },
    {.type = DEVICE_PATH_GENERIC, .generic.id = port, .generic.subid = 0}};
const struct device *conn = find_dev_nested_path(pci_root_bus(), conn_path,
    							ARRAY_SIZE(conn_path));
```

find_dev_nested_path will then find the PMC device and search its children for the connector with the given port