wireless: wcnss: compilation fixes for 64-bit platforms

Several small fixes so that the wcnss module shall compile on
32/64-bit platforms.

CRs-Fixed: 645621
Change-Id: I34cb18418f7f49ad27f75982499509b9e20ff2ed
Signed-off-by: Shete Mihir <smihir@codeaurora.org>