macros: Clean up bitfield macro by replacing the input item

Before:

    #[derive(BitField)]
    #[passthrough(derive(Clone, Copy, PartialEq))]
    pub struct TrbSchema {
        parameter: B64,
        status: B32,
        cycle: B1,
        flags: B9,
        trb_type: B6,
        control: B16,
    }

After:

    #[bitfield]
    #[derive(Clone, Copy, PartialEq)]
    pub struct Trb {
        parameter: B64,
        status: B32,
        cycle: B1,
        flags: B9,
        trb_type: B6,
        control: B16,
    }

This change eliminates the need for the `passthrough` attribute, and
avoids the separate `FooSchema` struct continuing to float around and
disrupt IDE autocomplete.

TEST=`cargo test` the bit_field_derive crate
TEST=`cargo check` the devices crate against a migrated CL:1144264

Change-Id: I950ce896607468c73852aa181827f1a5dc0f0227
Reviewed-on: https://chromium-review.googlesource.com/1366539
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: David Tolnay <dtolnay@chromium.org>
Reviewed-by: Jingkui Wang <jkwang@google.com>

0 files changed, 0 insertions, 0 deletions