Un-qualify use of defmt in proc macros

[jamesmunns]

Fixes #1021

This seems to resolve the issues I see in a basic test in embedded-hal.

[jamesmunns]

I'm open to suggestions on how to add a regression test for this, I'm not super familiar with defmt's test stack, but something as simple as this is enough to trigger at least a basic check:

cargo new dfmt-regress
cd dfmt-regress
cargo add embedded-hal --features=defmt-03
echo '[patch.crates-io]\ndefmt = { path = "PATH/TO/defmt/defmt" }' >> Cargo.toml
cargo check

[jonathanpallant]

Good catch, thanks! I don't know I'll be able to get a patch release out - maybe Monday?

[jamesmunns]

Not a huge deal/rush for now, for testing we've just tweaked defmt anyway and patched that too. Just wanted to share findings made along the way :)