staging: wilc1000: handle_set_mac_address: fix missing blank line after declaration

commit 31cc9885 ("staging: wilc1000: handle_set_mac_address: use kmemdup")
introduces a new checkpatch warning, so this patch fixes it.

WARNING: Missing a blank line after declarations
FILE: drivers/staging/wilc1000/host_interface.c:430:

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