rust_binder: fix needless borrow in context.rs

rust_binder: fix needless borrow in context.rs

Clippy warns about a needless borrow in context.rs:

    error: this expression creates a reference which is immediately dereferenced by the compiler
       --> drivers/android/binder/context.rs:141:18
        |
    141 |             func(&proc);
        |                  ^^^^^ help: change this to: `proc`

Remove the unnecessary borrow to satisfy clippy and improve code
cleanliness. No functional change.

Signed-off-by: Shivam Kalra <shivamklr@cock.li>
Acked-by: Alice Ryhl <aliceryhl@google.com>
Link: https://patch.msgid.link/20260130182842.217821-1-shivamklr@cock.li
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>