[PATCH] rust: devres: fix doctest build under `!CONFIG_PCI`

[Miguel Ojeda <ojeda@kernel.org>]

The doctest requires `CONFIG_PCI`:

    error[E0432]: unresolved import `kernel::pci`
        --> rust/doctests_kernel_generated.rs:2689:44
         |
    2689 | use kernel::{device::Core, devres::Devres, pci};
         |                                            ^^^ no `pci` in the root
         |
    note: found an item that was configured out
        --> rust/kernel/lib.rs:96:9
    note: the item is gated here
        --> rust/kernel/lib.rs:95:1

Thus conditionally compile it (which still checks the syntax).

Fixes: f301cb978c06 ("rust: devres: implement Devres::access()")
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
I noticed this in next-20250509 -- as usual, please feel free to fixup
it (or not) as preferred. Thanks!

 rust/kernel/devres.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/rust/kernel/devres.rs b/rust/kernel/devres.rs
index b67247db92c7..0f79a2ec9474 100644
--- a/rust/kernel/devres.rs
+++ b/rust/kernel/devres.rs
@@ -195,6 +195,7 @@ pub fn new_foreign_owned(dev: &Device<Bound>, data: T, flags: Flags) -> Result {
     /// # Example
     ///
     /// ```no_run
+    /// # #![cfg(CONFIG_PCI)]
     /// # use kernel::{device::Core, devres::Devres, pci};
     ///
     /// fn from_core(dev: &pci::Device<Core>, devres: Devres<pci::Bar<0x4>>) -> Result {

base-commit: ed61cb3d78d585209ec775933078e268544fe9a4
--
2.49.0