samples: rust: pci: take advantage of Devres::access()

For the I/O operations executed from the probe() method, take advantage
of Devres::access(), avoiding the atomic check and RCU read lock required
otherwise entirely.

Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Acked-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
Link: https://lore.kernel.org/r/20250428140137.468709-4-dakr@kernel.org
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

Author: Danilo Krummrich

samples/rust/rust_driver_pci.rs

@@ -83,12 +83,12 @@ impl pci::Driver for SampleDriver {
             GFP_KERNEL,
         )?;
 
-        let res = drvdata
-            .bar
-            .try_access_with(|b| Self::testdev(info, b))
-            .ok_or(ENXIO)??;
-
-        dev_info!(pdev.as_ref(), "pci-testdev data-match count: {}\n", res);
+        let bar = drvdata.bar.access(pdev.as_ref())?;
+        dev_info!(
+            pdev.as_ref(),
+            "pci-testdev data-match count: {}\n",
+            Self::testdev(info, bar)?
+        );
 
         Ok(drvdata.into())
     }