qcacld-3.0: Fix possible uninitialized variable access in wma_add_bss_sta_mode
In function wma_add_bss_sta_mode, variable "peer" is not initialized.
Possibly we may pass this variable to wma_remove_peer function as is
and that can be dereferenced inside wma_remove_peer function.
So initialize peer with NULL to avoid dereferencing uninitialized variable.
Change-Id: Ibc484759b5e92052a3500137464e47287ccad939
CRs-Fixed: 1042968