Revert "[Zion][Yellowstone] First pass at adding PCI ioport access."

This reverts commit b677633248.

rust/lib/mammoth/src/syscall.rs

@@ -472,25 +472,3 @@ pub fn semaphone_wait(sem_cap: &Capability) -> Result<(), ZError> {
         },
     )
 }
-
-pub fn pci_read(
-    pci_cap: &Capability,
-    bus: u8,
-    slot: u8,
-    func: u8,
-    offset: u8,
-) -> Result<u32, ZError> {
-    let mut data: u32 = 0;
-    syscall(
-        zion::kZionPciRead,
-        &zion::ZPciReadReq {
-            pci_cap: pci_cap.raw(),
-            bus,
-            slot,
-            func,
-            offset,
-            output: &mut data as *mut u32,
-        },
-    )?;
-    Ok(data)
-}