build: Remove the exposed "cmos" feature

This only affects the build system; the feature was already always
compiled in with ca68b9e7a9

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

devices/Cargo.toml

@@ -25,5 +25,4 @@ arch = { path = "../arch" }
 
 [features]
 default = []
-cmos = []
 fwdebug = []