wlan: Add driver cmd MAXTXPOWER

Provide interface to set maxtxpower.

Change-Id: Icc31df69778d8a45ca0cf47ce1be6f0118d9479a
CRs-Fixed: 2064549
diff --git a/CORE/HDD/inc/wlan_hdd_main.h b/CORE/HDD/inc/wlan_hdd_main.h
index b36e185..45a0f0b 100644
--- a/CORE/HDD/inc/wlan_hdd_main.h
+++ b/CORE/HDD/inc/wlan_hdd_main.h
@@ -263,6 +263,8 @@
 #define MDNS_TTL                                  5
 #endif /* MDNS_OFFLOAD */
 
+#define HDD_MIN_TX_POWER (-100) /* minimum tx power */
+#define HDD_MAX_TX_POWER (+100)  /* maximum tx power */
 /*
  * Generic asynchronous request/response support
  *