uefi: Fix unused-unsafe warning depending on enabled features

If neither the logger nor global_allocator features is enabled, the unsafe block
here would generated a warning because there was no code in it. Split into two
blocks and gate the blocks behind cfgs to solve this.

Author: nicholasbishop

uefi/src/helpers/mod.rs

@@ -83,13 +83,15 @@ pub fn init(st: &mut SystemTable<Boot>) -> Result<()> {
     // Setup the system table singleton
     SYSTEM_TABLE.store(st.as_ptr().cast_mut(), Ordering::Release);
 
-    unsafe {
-        // Setup logging and memory allocation
+    // Setup logging and memory allocation
 
-        #[cfg(feature = "logger")]
+    #[cfg(feature = "logger")]
+    unsafe {
         logger::init(st);
+    }
 
-        #[cfg(feature = "global_allocator")]
+    #[cfg(feature = "global_allocator")]
+    unsafe {
         uefi::allocator::init(st);
     }