qcacld-3.0: Add feature flag for dp rx buffer cache

Add feature flag PEER_CACHE_RX_PKTS to support caching RX
buffers in dp.

Change-Id: Ie8cc7368568554c5320889cbb9ca8db4532cb03e
CRs-Fixed: 2442779
diff --git a/Kbuild b/Kbuild
index a308e8d..129d051 100644
--- a/Kbuild
+++ b/Kbuild
@@ -2683,6 +2683,7 @@
 endif
 
 cppflags-y += -DFEATURE_NBUFF_REPLENISH_TIMER
+cppflags-y += -DPEER_CACHE_RX_PKTS
 
 ccflags-$(CONFIG_HASTINGS_BT_WAR) += -DHASTINGS_BT_WAR