[L] Change in coreboot[main]: intelp2m: add support for elkhartlake

[Maxim (Code Review)]

Attention is currently required from: Alexander Couzens.

Maxim has posted comments on this change by Alexander Couzens. ( https://review.coreboot.org/c/coreboot/+/84191?usp=email )

Change subject: intelp2m: add support for elkhartlake
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Patch Set 3:

(6 comments)

Patchset:

PS3: 
Thanks for this work!

It seems that the code in all methods is the same as the Apollo Lake platform (https://review.coreboot.org/plugins/gitiles/coreboot/+/refs/heads/main/util/...), except for `func (Platform Specific) Pull() {...}`. And if so, we can reuse these methods. It is necessary to define InheritanceMacro : apl.Platform Specific{} inside the structure for the new platform and make calls in the appropriate methods. (for example, for Cannon Lake - https://review.coreboot.org/plugins/gitiles/coreboot/+/refs/heads/main/util/...)

File util/intelp2m/platforms/ehl/macro.go:

https://review.coreboot.org/c/coreboot/+/84191/comment/5caf1b86_411e922b?usp... :
PS3, Line 151: func (PlatformSpecific) GpiMacroAdd() {
```go
// Adds PAD_CFG_GPI macro with arguments
func (PlatformSpecific) GpiMacroAdd() {
    platform.InheritanceMacro.GpiMacroAdd()
}
```

https://review.coreboot.org/c/coreboot/+/84191/comment/23fa57ec_7f4a90e5?usp... :
PS3, Line 204: func (PlatformSpecific) GpoMacroAdd() {
```go
// Adds PAD_CFG_GPO macro with arguments
func (platform PlatformSpecific) GpoMacroAdd() {
    platform.InheritanceMacro.GpoMacroAdd()
}
```

https://review.coreboot.org/c/coreboot/+/84191/comment/11d578d5_622929a8?usp... :
PS3, Line 236: func (PlatformSpecific) NativeFunctionMacroAdd() {
```go
// Adds PAD_CFG_NF macro with arguments
func (platform PlatformSpecific) NativeFunctionMacroAdd() {
    platform.InheritanceMacro.NativeFunctionMacroAdd()
}
```

https://review.coreboot.org/c/coreboot/+/84191/comment/ff3a718a_fd94b7cd?usp... :
PS3, Line 268: func (PlatformSpecific) NoConnMacroAdd() {
```go
// Adds PAD_NC macro
func (platform PlatformSpecific) NoConnMacroAdd() {
    platform.InheritanceMacro.NoConnMacroAdd()
}
```

https://review.coreboot.org/c/coreboot/+/84191/comment/d839a88b_5cd5027e?usp... :
PS3, Line 302: 	macro := common.GetInstanceMacro(PlatformSpecific{}, fields.InterfaceGet())
```go
    macro := common.GetInstanceMacro(
    	PlatformSpecific{
    		InheritanceMacro: apl.PlatformSpecific{},
    	},
    	fields.InterfaceGet(),
    )
```