staging: wilc1000: remove unnecessary wilc_rx_complete function

This patch remove unnecessary wilc_rx_complete function
because this function only print unused log message.
remove unused has_packet variable nomore.

Signed-off-by: Chris Park <chris.park@atmel.com>
Signed-off-by: Leo Kim <leo.kim@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>