staging: wilc1000: call power save after changing mode

host_int_set_power_mgmt should be called after changing operation mode to
work properly. Move the function below host_int_set_operation_mode.

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