Remove mistaken commit

Signed-off-by: Alper Polat <gitperr@gmail.com>

collector/exec_bsd.go

@@ -59,7 +59,6 @@ func NewExecCollector(logger log.Logger) (Collector, error) {
 				name:        "exec_system_calls_total",
 				description: "System calls since system boot.  Resets at architecture unsigned integer.",
 				mib:         "vm.stats.sys.v_syscall",
-				labels:      nil,
 			},
 			{
 				name:        "exec_device_interrupts_total",