qcacmn: Use IS_ENABLED for the definition of kernel module

Add code to use IS_ENABLED for CONFIG_WCNSS_MEM_PRE_ALLOC
kernel modules and remove inclusion of reduntant header
file cnss.h.

Change-Id: If1d098c7c6f326d12700f06318909a7fc0e7895a
CRs-fixed: 2702368
2 files changed