Fix clippy errors

kernel/src/arch/x86_64/memory.rs

@@ -55,7 +55,7 @@ pub unsafe fn init(physical_memory_offset: VirtAddr) -> OffsetPageTable<'static>
     }
 }
 
-pub(crate) struct FoundryOSFrameAllocator {
+pub struct FoundryOSFrameAllocator {
     memory_map: &'static MemoryMapResponse,
     next: usize,
 }
@@ -66,8 +66,8 @@ impl FoundryOSFrameAllocator {
     /// This function takes a reference to a `MemoryMapResponse` and initializes a
     /// `FoundryOSFrameAllocator` with it. The `next` field is set to 0, indicating that
     /// the first frame to be allocated is the first frame in the memory map.
-    pub unsafe fn init(memory_map: &'static MemoryMapResponse) -> FoundryOSFrameAllocator {
-        FoundryOSFrameAllocator {
+    pub const unsafe fn init(memory_map: &'static MemoryMapResponse) -> Self {
+        Self {
             memory_map,
             next: 0,
         }