staging: wilc1000: rename u8mode of struct host_if_wep_attr

This patch renames u8mode of struct host_if_wep_attr to mode to avoid
CamelCase naming convention.

Signed-off-by: Tony Cho <tony.cho@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>