vm-allocator: Remove a redundant check for zero

alignment.is_power_of_two() already implies alignment != 0.

Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>

vm-allocator/src/address.rs

@@ -174,7 +174,7 @@ impl AddressAllocator {
         }
 
         let alignment = align_size.unwrap_or(4);
-        if !alignment.is_power_of_two() || alignment == 0 {
+        if !alignment.is_power_of_two() {
             return None;
         }