qcacld-3.0: Add flag for increased Tx descs

Add flag for increased Tx descs. And Enable the flag for qca6490.
Based on 1Tx:8Rx NAN test case experiment, it requires increase in
Tx descriptors to burst trafficto each Rx device.

Change-Id: I364ada1ee80afcaf3db3d50efa16a95054a4f7f4
CRs-Fixed: 2658549
diff --git a/Kbuild b/Kbuild
index bfcb392..f99d66e 100644
--- a/Kbuild
+++ b/Kbuild
@@ -3198,6 +3198,8 @@
 
 cppflags-$(CONFIG_RX_FISA) += -DWLAN_SUPPORT_RX_FISA
 
+cppflags-$(CONFIG_MORE_TX_DESC) += -DTX_TO_NPEERS_INC_TX_DESCS
+
 ccflags-$(CONFIG_HASTINGS_BT_WAR) += -DHASTINGS_BT_WAR
 
 cppflags-$(CONFIG_SLUB_DEBUG_ON) += -DHIF_CONFIG_SLUB_DEBUG_ON