qcacmn: Fix build error when MEMORY_DEBUG disabled

Move is_initial_mem_debug_disabled under MEMORY_DEBUG flag as it
does not depend on NBUF_MEMORY_DEBUG to fix un-usued symbol error
when MEMORY_DEBUG is disable and NBUF_MEMORY_DEBUG is enable.

Change-Id: Idb54544321a0fd9dda7a6e98d91d22d01be50e41

qdf/linux/src/qdf_mem.c

@@ -47,6 +47,9 @@
 static bool mem_debug_disabled;
 qdf_declare_param(mem_debug_disabled, bool);
 qdf_export_symbol(mem_debug_disabled);
+#endif
+
+#ifdef MEMORY_DEBUG
 static bool is_initial_mem_debug_disabled;
 #endif