qcacld-3.0: Replace hdd_adapter_t in wlan_hdd_subnet_detect.c
The Linux Coding Style enumerates a few special cases where typedefs
are useful, but stresses "NEVER EVER use a typedef unless you can
clearly match one of those rules." The hdd_adapter_t typedef does not
meet any of those criteria, so replace references to it with a
reference to the underlying struct.
Change-Id: I66f20697851fdace617463b068c38ba63f4a07e0
CRs-Fixed: 2101033