staging: wilc1000: Remove return variables from wilc_spi.c

Remove return variables from wilc_spi.c. Issue found with Coccinelle
using ret.cocci.

Signed-off-by: Nishka Dasgupta <nishka.dasgupta@yahoo.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>