qcacmn: Possible buffer overflow while copying rnr info

A temporary variable "temp" is declared to use it while sorting
the channels based on the weightage/rnr info. This is declared
as a pointer to hold the reference of struct rnr_chan_weight but
memcpy is done to this without allocating memory.
Declare this as a variable instead of pointer to use it as an
intermediate variable for sorting.

Change-Id: If619f5fa462d5400f0a77e57317ac3c8debb34a5
CRs-Fixed: 2842819