Wlan: Incorrect pointer arithmetic comparison

typecast  to a more generic type like uintptr_t for pointer arithmetic
so  that  it works correctly on both 32 bit and 64 bit implementations

Change-Id: Ifd55a4af08e4fddbd20b60d3702385196816a41a
CRs-Fixed: 638969
wlan : Revision 3.2.3.291

 Revision  3.2.3.291

Change-Id: I42167c3d5fd98cd2539332c1428d851902670291