qcacld-3.0: Remove obsolete wma_map_channel() prototype

The driver contains a prototype for wma_map_channel() but no
implementation, so remove the prototype.

Change-Id: I1a8794c103ac78df8ef4fd1c181ee60350c88058
CRs-Fixed: 2365054

core/wma/inc/wma_api.h

@@ -131,8 +131,6 @@ bool wma_needshutdown(void);
 
 QDF_STATUS wma_wait_for_ready_event(WMA_HANDLE handle);
 
-uint8_t wma_map_channel(uint8_t mapChannel);
-
 int wma_cli_get_command(int vdev_id, int param_id, int vpdev);
 int wma_cli_set_command(int vdev_id, int param_id, int sval, int vpdev);
 int wma_cli_set2_command(int vdev_id, int param_id, int sval1,