staging: wilc1000: remove unused hif_drv in wilc_del_beacon

This patch removes unused hif_drv in wilc_del_beacon.
There is no need to check null and print debug log.

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