qcacmn: Fix qdf_get_monotonic_boottime_ns()

Fix the API implementation to account for time spent in system
suspend. This matches with API qdf_get_monotonic_boottime()
implementation.

Change-Id: I4bf8980bfc4500c035e8de7df4d8a18dfc6775ae
CRs-Fixed: 2211953

qdf/inc/qdf_mc_timer.h

@@ -263,7 +263,7 @@ unsigned long qdf_mc_timer_get_system_time(void);
 /**
  * qdf_get_monotonic_boottime_ns() - Get kernel boottime in ns
  *
- * Return: kernel boottime in nano sec
+ * Return: kernel boottime in nano sec (includes time spent in suspend)
  */
 s64 qdf_get_monotonic_boottime_ns(void);