Fix unused Results

[jonlamb-gh]

warning: unused `core::result::Result` that must be used
   --> ferros/src/userland/multi_consumer.rs:705:5
    |
705 |     consumer_vspace.skip_pages(1);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: `#[warn(unused_must_use)]` on by default
    = note: this `Result` may be an `Err` variant, which should be handled

warning: unused `core::result::Result` that must be used
   --> ferros/src/userland/multi_consumer.rs:713:5
    |
713 |     consumer_vspace.skip_pages(1);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: this `Result` may be an `Err` variant, which should be handled

[jonlamb-gh]

Fixed as of 9c75775.