qcacmn: Do not directly alias 'struct timer_list'

There are a number of places where the kernel's timer_list type has been
used in conjunction with qdf_timer APIs. To prevent reintroduction of
similar issues in the future, do not directly alias qdf_timer_t to
timer_list.

See also: I410b7fafad18be01141008b6220fbe34ab07601e

Change-Id: Ic4cef0d6301230197443d4d5247188f2af643674
CRs-Fixed: 2388595