espi: Mark W1C bits accordingly

[felipebalbi]

These bits are Write-1-to-clear, let's mark them accordingly so svd2rust generates the correct accessors for us.

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src/espi/mstat.rs:8

• [nitpick] The type name P80intR is inconsistent with the naming convention. It should be renamed to P80IntR.

pub type P80intR = crate::BitReader;