[rdkb][common][app][Refactor struct ap_param to interface_param]

[Description]
Change variable and function names from ap to interface. Naming align openwrt.
Because the struct would not only be used by ap.
[Release-log]
N/A

Change-Id: I4be8d1f5ce2d12cf414d599a54736eb3c9d74a70
2 files changed