HV: Remove the check pcpu active status when sending INIT

Intel SDM Vol3 23.8 says:
  The INIT signal is blocked whenever a logical processor is in VMX root operation.
  It is not blocked in VMX nonroot operation. Instead, INITs cause VM exits

So, there is no side-effect to send INIT signal regardless of pcpu active status.

Tracked-On: #2865
Signed-off-by: Kaige Fu <kaige.fu@intel.com>
Acked-by: Anthony Xu <anthony.xu@intel.com>

hypervisor/include/arch/x86/lapic.h

@@ -128,6 +128,8 @@ void send_single_ipi(uint16_t pcpu_id, uint32_t vector);
  * @brief Send an INIT signal to a single pCPU
  *
  * @param[in] pcpu_id The id of destination physical cpu
+ *
+ * @return None
  */
 void send_single_init(uint16_t pcpu_id);