bxcan: Make `bxcan` a hard dependency
There seems no way to enable a optional dependency from build.rs or
features passed through the command line.
@@ -26,7 +26,7 @@ bare-metal = "1.0.0"
atomic-polyfill = "0.1.3"
stm32-metapac = { version = "0.1.0", path = "../stm32-metapac", features = ["rt"] }
vcell = { version = "0.1.3", optional = true }
-bxcan = { version = "0.5.1" } # TODO: , optional = true }
+bxcan = { version = "0.5.1" }
cfg-if = "1.0.0"
