staging: vt6655: remove header declarations for static functions

The functions iwctl_giwscan() and iwctl_siwscan() are only referenced
within iwctl.c -- so, remove their function declarations from iwctl.h
and mark these functions as static.

Signed-off-by: James A Shackleford <shack@linux.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>