fix parted of "missing for discarded return value"

MISRA C required that return value should be used, missing for it should
add "(void)" prefix before the function call.
Some function can be declared without return value to avoid this problem.

Signed-off-by: Huihuang Shi <huihuang.shi@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>

hypervisor/arch/x86/intr_lapic.c

@@ -316,10 +316,9 @@ void resume_lapic(void)
 	restore_lapic(&saved_lapic_regs);
 }
 
-int send_lapic_eoi(void)
+void send_lapic_eoi(void)
 {
 	write_lapic_reg32(LAPIC_EOI_REGISTER, 0);
-	return 0;
 }
 
 static void wait_for_delivery(void)