staging: wilc1000: rename variable gu8FlushedJoinReqDrvHandler

This patch renames variable gu8FlushedJoinReqDrvHandler to join_req_drv
to avoid CamelCase naming convention.

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