staging: wilc1000: rename enuHostIFstate of struct host_if_drv

This patch renames enuHostIFstate of struct host_if_drv to hif_state
to avoid CamelCase naming convention.
And, some comments modification that has been included name 'enuHostIFstate'.

Signed-off-by: Leo Kim <leo.kim@atmel.com>
Signed-off-by: Glen Lee <glen.lee@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>