qcacld-3.0: fix prealloc not effective in Kbuild

Kbuild should contain build option CONFIG_WCNSS_MEM_PRE_ALLOC,
so we can enable prealloc feature.

Change-Id: I8e9acc83f7c0b36dad2f12cc88f028cc6a10d9ea
CRs-Fixed: 2706137

Kbuild

@@ -3003,6 +3003,7 @@ endif
 endif
 
 cppflags-$(CONFIG_FEATURE_SKB_PRE_ALLOC) += -DFEATURE_SKB_PRE_ALLOC
+cppflags-$(CONFIG_WCNSS_MEM_PRE_ALLOC) += -DCONFIG_WCNSS_MEM_PRE_ALLOC
 
 #Enable USB specific APIS
 ifeq ($(CONFIG_HIF_USB), y)