hv: treewide: fix 'Empty parameter list to procedure/function'

Use func(void) rather than func() for the function declaration and
definition based on MISRAC requirement.

Signed-off-by: Shiqing Gao <shiqing.gao@intel.com>
Reviewed-by: Junjie Mao <junjie.mao@intel.com>

hypervisor/include/arch/x86/cpu.h

@@ -328,8 +328,8 @@ bool cpu_has_cap(uint32_t bit);
 void load_cpu_state_data(void);
 void bsp_boot_init(void);
 void cpu_secondary_init(void);
-void start_cpus();
-void stop_cpus();
+void start_cpus(void);
+void stop_cpus(void);
 
 /* Read control register */
 #define CPU_CR_READ(cr, result_ptr)                         \