staging: wilc1000: remove _tstrJoinParam from join_bss_param

This patch removes struct _tstrJoinParam from the struct join_bss_param
because it is not used inside the struct.

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>