qcacld-3.0: Enable preallocation for rx buffer pool

Nbuf allocation failure is observed when refill rx buffers
due to momentary low memory.
To fix this, enable feature Rx prealloc buffer pool.

Change-Id: I111d84f3ad5b33024e6add4bed7561ae58e1a018
CRs-Fixed: 2841734

configs/default_defconfig

@@ -289,6 +289,9 @@ CONFIG_QCACLD_FEATURE_METERING := y
 CONFIG_WDI3_STATS_UPDATE := y
 ifeq ($(CONFIG_CNSS_QCA6490), y)
 CONFIG_WBM_IDLE_LSB_WR_CNF_WAR := y
+CONFIG_WLAN_FEATURE_RX_BUFFER_POOL := y
+CONFIG_DP_RX_BUFFER_POOL_SIZE := 128
+CONFIG_DP_RX_BUFFER_POOL_ALLOC_THRES := 5
 endif
 endif