Change in coreboot[master]: mb/google/brya/var/felwinter: Add stylus probe for garage

[Tim Wawrzynczak (Code Review)]

Attention is currently required from: Nick Vaccaro, EricR Lai.
Tim Wawrzynczak has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/60073 )

Change subject: mb/google/brya/var/felwinter: Add stylus probe for garage
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Patch Set 1: Code-Review+1

(2 comments)

Commit Message:

https://review.coreboot.org/c/coreboot/+/60073/comment/a0a1c672_0e3bc8d7 
PS1, Line 9: garage driver only attach to stylus sku.
suggestion:
```
Add a FW_CONFIG field to indicate stylus presence and add a probe
statement to the devicetree for the corresponding device
```

File src/mainboard/google/brya/variants/felwinter/overridetree.cb:

https://review.coreboot.org/c/coreboot/+/60073/comment/df625478_8e75edb6 
PS1, Line 9: PRSENT
`PRESENT`
?