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>

Cargo.toml

@@ -56,7 +56,6 @@ wait-timeout = "0.2.0"
 default = ["common", "kvm"]
 # Common features for all hypervisors
 common = ["fwdebug"]
-cmos = ["vmm/cmos"]
 fwdebug = ["vmm/fwdebug"]
 gdb = ["vmm/gdb"]
 guest_debug = ["vmm/guest_debug"]