uefi: Consistently use &mut self for pxe::BaseCode methods

Although these methods are just reading data, they are almost certainly
modifying internal state in the UEFI protocol and so should be `&mut`.

Author: nicholasbishop

uefi/CHANGELOG.md

@@ -9,6 +9,9 @@
 - **Breaking:** Removed `BootPolicyError` as `BootPolicy` construction is no
   longer fallible. `BootPolicy` now tightly integrates the new `Boolean` type
   of `uefi-raw`.
+- **Breaking:** The `pxe::BaseCode::tftp_read_dir` and
+  `pxe::BaseCode::mtftp_read_dir` methods now take `&mut self` instead of
+  `&self`.
 - `boot::memory_map()` will never return `Status::BUFFER_TOO_SMALL` from now on,
   as this is considered a hard internal error where users can't do anything
   about it anyway. It will panic instead.

uefi/src/proto/network/pxe.rs

@@ -233,7 +233,7 @@ impl BaseCode {
 
     /// Reads a directory listing of a directory on a TFTP server.
     pub fn tftp_read_dir<'a>(
-        &self,
+        &mut self,
         server_ip: &IpAddress,
         directory_name: &CStr8,
         buffer: &'a mut [u8],
@@ -366,7 +366,7 @@ impl BaseCode {
 
     /// Reads a directory listing of a directory on a MTFTP server.
     pub fn mtftp_read_dir<'a>(
-        &self,
+        &mut self,
         server_ip: &IpAddress,
         buffer: &'a mut [u8],
         info: &MtftpInfo,