qcacld-3.0: Remove tSirBackgroundScanMode

Change Ia664f815759142e7f4ad8e648a469c63ddd003f5 ("qcacld-3.0:
Cleanup unused scan code") removed the last reference to
tSirBackgroundScanMode. Since it is now obsolete, remove it.

Change-Id: I2faab5487988b1941601f2befdb570ecab8651ed
CRs-Fixed: 2374282

core/mac/inc/sir_api.h

@@ -743,11 +743,6 @@ typedef struct sSirChannelList {
 	uint8_t channelNumber[SIR_ESE_MAX_MEAS_IE_REQS];
 } tSirChannelList, *tpSirChannelList;
 
-/* / Two Background Scan mode */
-typedef enum eSirBackgroundScanMode {
-	eSIR_ROAMING_SCAN = 2,
-} tSirBackgroundScanMode;
-
 #ifdef FEATURE_OEM_DATA_SUPPORT
 struct oem_data_req {
 	uint32_t data_len;