Switch back to automatic Debug derive for Header struct

The `Header` `Debug` implementation was accidentally printing the `size`
field for the `signature`. Rather than just fix that field, switch the
whole thing back to using `derive(Debug)`. This adds in the `_reserved`
field, which probably doesn't matter much either way but might as well
show the whole struct when debug printing.

Author: nicholasbishop

src/table/header.rs

@@ -1,7 +1,7 @@
 use super::Revision;
-use core::fmt::{Debug, Formatter};
 
 /// All standard UEFI tables begin with a common header.
+#[derive(Debug)]
 #[repr(C)]
 pub struct Header {
     /// Unique identifier for this table.
@@ -16,14 +16,3 @@ pub struct Header {
     /// Reserved field that must be set to 0.
     _reserved: u32,
 }
-
-impl Debug for Header {
-    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
-        f.debug_struct("Header")
-            .field("signature", &(self.size as *const u64))
-            .field("revision", &self.revision)
-            .field("size", &self.size)
-            .field("crc", &self.crc)
-            .finish()
-    }
-}