staging: wilc1000: move variable clients_count

This patch moves static variable clients_count to around where the local
variables are togther.

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>