staging: wlan-ng: Remove function prism2mib_excludeunencrypted()

Remove function prism2mib_excludeunencrypted as all it does is call
prism2mib_flag.
Modify call sites accordingly.
Issue found with Coccinelle.

Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
Link: https://lore.kernel.org/r/20190802060913.30241-1-nishkadg.linux@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>