qcacld-3.0: Remove typedef tSirwifiTxRate

Typedef tSirwifiTxRate is obsolete, so remove it.

Change-Id: I0ca020e4033d4737bc4ee6bff1a13f2343847f8e
CRs-Fixed: 2376930

core/mac/inc/sir_api.h

@@ -3686,7 +3686,6 @@ typedef struct {
 
 typedef int tSirWifiRadio;
 typedef int tSirWifiChannel;
-typedef int tSirwifiTxRate;
 
 typedef struct {
 	uint32_t reqId;