Merge pull request #6899 from bergzand/drivers/mrf24j40-remdefine

drivers/mrf24j40 remove obsolete RSSI_BASE_VALUE define

drivers/include/mrf24j40.h

@@ -75,11 +75,6 @@ extern "C" {
  *  31 -> -0dB
  */
 
-/**
- * @brief   Base (minimal) RSSI value in dBm
- */
-#define RSSI_BASE_VAL                   (-91)
-
 /**
  * @brief   Flags for PSEUDO DEVICE INTERNAL STATES
  * @{