samples: rust: fix endianness issue in rust_driver_pci

samples: rust: fix endianness issue in rust_driver_pci

MMIO backend of PCI Bar always assumes little-endian devices and
will convert to CPU endianness automatically. Remove the u32::from_le
conversion which would cause a bug on big-endian machines.

Cc: stable@vger.kernel.org
Reviewed-by: Dirk Behme <dirk.behme@de.bosch.com>
Signed-off-by: Marko Turk <mt@markoturk.info>
Fixes: 685376d18e9a ("samples: rust: add Rust PCI sample driver")
Link: https://patch.msgid.link/20251210112503.62925-2-mt@markoturk.info
Signed-off-by: Danilo Krummrich <dakr@kernel.org>