staging/wilc1000: move wilc_wlan_inp_t into struct wilc

wilc_wlan_inp_t is an unnecessary indirection and requires linux_wlan.c
to have knowledge of the specific sdio and spi front-ends. This
removes the structure and places io_type directly inside the struct wilc.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>