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