target-mips: Remove commented-out function declaration

There is no function cpu_mips_get_clock(), so drop it.
Signed-off-by: NAndreas Färber <afaerber@suse.de>
Acked-by: NStefan Weil <sw@weilnetz.de>

target-mips/cpu.h

@@ -627,7 +627,6 @@ enum {
 
 int cpu_mips_exec(CPUMIPSState *s);
 CPUMIPSState *cpu_mips_init(const char *cpu_model);
-//~ uint32_t cpu_mips_get_clock (void);
 int cpu_mips_signal_handler(int host_signum, void *pinfo, void *puc);
 
 /* mips_timer.c */