arch: reevaluate #[allow] attributes

Remove stale #[allow]s whose lints no longer fire (a module-level
non_camel_case_types in mpspec, and a too_many_arguments on a riscv64
configure_system that no longer exceeds the argument threshold), and
convert the still-needed ones to #[expect].

Part of #8326.

Signed-off-by: Tushar Khatri <hello@tusharkhatri.in>

arch/src/aarch64/fdt.rs

@@ -204,7 +204,7 @@ pub fn get_cache_shared(cache_level: CacheLevel) -> bool {
 }
 
 /// Creates the flattened device tree for this aarch64 VM.
-#[allow(clippy::too_many_arguments)]
+#[expect(clippy::too_many_arguments)]
 pub fn create_fdt<T: DeviceInfoForFdt + Clone + Debug, S: ::std::hash::BuildHasher>(
     guest_mem: &GuestMemoryMmap,
     cmdline: &str,

arch/src/aarch64/mod.rs

@@ -121,7 +121,7 @@ pub fn arch_memory_regions() -> Vec<(GuestAddress, usize, RegionType)> {
 }
 
 /// Configures the system and should be called once per vm before starting vcpu threads.
-#[allow(clippy::too_many_arguments)]
+#[expect(clippy::too_many_arguments)]
 pub fn configure_system<T: DeviceInfoForFdt + Clone + Debug, S: ::std::hash::BuildHasher>(
     guest_mem: &GuestMemoryMmap,
     cmdline: &str,

arch/src/riscv64/fdt.rs

@@ -61,7 +61,7 @@ pub enum Error {
 type Result<T> = result::Result<T, Error>;
 
 /// Creates the flattened device tree for this riscv64 VM.
-#[allow(clippy::too_many_arguments)]
+#[expect(clippy::too_many_arguments)]
 pub fn create_fdt<T: DeviceInfoForFdt + Clone + Debug, S: ::std::hash::BuildHasher>(
     guest_mem: &GuestMemoryMmap,
     cmdline: &str,

arch/src/riscv64/mod.rs

@@ -160,7 +160,6 @@ fn isa_string_from_host() -> Result<String, Error> {
 }
 
 /// Configures the system and should be called once per vm before starting vcpu threads.
-#[allow(clippy::too_many_arguments)]
 pub fn configure_system<T: DeviceInfoForFdt + Clone + Debug, S: ::std::hash::BuildHasher>(
     guest_mem: &GuestMemoryMmap,
     cmdline: &str,

arch/src/x86_64/mod.rs

@@ -913,7 +913,7 @@ fn common_cpuid_tdx_configuration(
     Ok(())
 }
 
-#[allow(clippy::too_many_arguments)]
+#[expect(clippy::too_many_arguments)]
 pub fn configure_vcpu(
     vcpu: &dyn hypervisor::Vcpu,
     id: u32,
@@ -1053,7 +1053,7 @@ pub fn arch_memory_regions() -> Vec<(GuestAddress, usize, RegionType)> {
 /// * `cmdline_addr` - Address in `guest_mem` where the kernel command line was loaded.
 /// * `cmdline_size` - Size of the kernel command line in bytes including the null terminator.
 /// * `num_cpus` - Number of virtual CPUs the guest will have.
-#[allow(clippy::too_many_arguments)]
+#[expect(clippy::too_many_arguments)]
 pub fn configure_system(
     guest_mem: &GuestMemoryMmap,
     cmdline_addr: GuestAddress,

arch/src/x86_64/mpspec.rs

@@ -3,7 +3,6 @@
 // SPDX-License-Identifier: Apache-2.0 AND BSD-3-Clause
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE-BSD-3-Clause file.
-#![allow(non_camel_case_types)]
 use vm_memory::ByteValued;
 
 pub const MP_PROCESSOR: ::std::os::raw::c_uint = 0;