staging: wilc1000: rename pstrHiddenNetwork in wilc_scan

This patch renames pstrHiddenNetwork to hidden_network to avoid
camelcase.

Signed-off-by: Chaehyun Lim <chaehyun.lim@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>