wlan: Add INI param to change VHT AMPDU length exponent in VHT IE

Added an INI param gVhtMaxAmpduLenExp to modify the value of
VHT AMPDU length exponent. Default value of VHT AMPDU length
exponent is 3.

Change-Id: I042b857666d7af55bfb8993346432c8865c85a63
CRs-Fixed: 748261
diff --git a/CORE/HDD/inc/wlan_hdd_cfg.h b/CORE/HDD/inc/wlan_hdd_cfg.h
index 8d0b9c4..2c89f46 100644
--- a/CORE/HDD/inc/wlan_hdd_cfg.h
+++ b/CORE/HDD/inc/wlan_hdd_cfg.h
@@ -1939,6 +1939,11 @@
 #define CFG_VHT_ENABLE_MU_BFORMEE_CAP_FEATURE_MAX     ( 1 )
 #define CFG_VHT_ENABLE_MU_BFORMEE_CAP_FEATURE_DEFAULT ( 1 )
 
+#define CFG_VHT_AMPDU_LEN_EXP_NAME          "gVhtMaxAmpduLenExp"
+#define CFG_VHT_AMPDU_LEN_EXP_MIN           ( 0 )
+#define CFG_VHT_AMPDU_LEN_EXP_MAX           ( 7 )
+#define CFG_VHT_AMPDU_LEN_EXP_DEFAULT       ( 3 )
+
 #endif
 
 
@@ -2697,6 +2702,7 @@
    v_BOOL_t                    enableTxBF;
    v_U8_t                      txBFCsnValue;
    v_BOOL_t                    enableMuBformee;
+   v_U8_t                      gVhtMaxAmpduLenExp;
 #endif
    v_U8_t                      enableModulatedDTIM;
    v_U32_t                     fEnableMCAddrList;