package/cargo-bin: install if rust-bin selected

package/cargo-bin: install if rust-bin selected

If host-rust-bin, the pre-built Rust compiler, is selected as a rustc
provider, then also install the pre-built cargo binary to be coherent.

Signed-off-by: Eric Le Bihan <eric.le.bihan.dev@free.fr>
Signed-off-by: Patrick Havelange <patrick.havelange@essensium.com>
[Arnout: don't install cargo config, alread moved]
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Reviewed-by: David Pierret <david.pierret@smile.fr>
Tested-by: David Pierret <david.pierret@smile.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>