samples: rust: pci: Remove some additional `.as_ref()` for `dev_*` print

samples: rust: pci: Remove some additional `.as_ref()` for `dev_*` print

The commit 600de1c008b2 ("rust: pci: remove redundant `.as_ref()` for
`dev_*` print") removed `.as_ref()` for `dev_*` prints. Nearly at the
same time the commit e62e48adf76c ("sample: rust: pci: add tests for
config space routines") was merged. Which missed this removal, then.

Signed-off-by: Dirk Behme <dirk.behme@de.bosch.com>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Link: https://patch.msgid.link/20260202064001.176787-1-dirk.behme@de.bosch.com
Signed-off-by: Danilo Krummrich <dakr@kernel.org>