rust: remove pr_cont from prelude

`pr_cont` is a discouraged feature. While we still support it in
print.rs, remove it from the prelude so it's less likely to get used.

Signed-off-by: Gary Guo <gary@garyguo.net>

Author: nbdd0121

rust/kernel/prelude.rs

@@ -17,7 +17,7 @@ pub use super::build_assert;
 
 pub use module::{module, module_misc_device};
 
-pub use super::{pr_alert, pr_cont, pr_crit, pr_emerg, pr_err, pr_info, pr_notice, pr_warn};
+pub use super::{pr_alert, pr_crit, pr_emerg, pr_err, pr_info, pr_notice, pr_warn};
 
 pub use super::static_assert;
 

samples/rust/rust_print.rs

@@ -5,6 +5,7 @@
 #![no_std]
 #![feature(allocator_api, global_asm)]
 
+use kernel::pr_cont;
 use kernel::prelude::*;
 
 module! {