staging: wilc1000: remove unnecessary files

This patch removes the following files which are not used anymore.
	- fifo_buffer.c
	- fifo_buffer.h
	- coreconfigsimulator.h
	- wilc_wfi_netdevice.c

Signed-off-by: Robin Hwang <robin.hwang@atmel.com>
Signed-off-by: Tony Cho <tony.cho@atmel.com>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>