staging/wilc1000: fix Kconfig dependencies

The newly added wilc1000 driver lacks several Kconfig dependencies,
resulting in a multitude of randconfig build errors, e.g.:

drivers/built-in.o: In function `WILC_WFI_mgmt_tx_cancel_wait':
binder.c:(.text+0x12bd28): undefined reference to `cfg80211_remain_on_channel_expired'
drivers/built-in.o: In function `WILC_WFI_CfgSetChannel':
binder.c:(.text+0x12c9d8): undefined reference to `ieee80211_frequency_to_channel'
drivers/built-in.o: In function `WILC_WFI_CfgAlloc':
binder.c:(.text+0x132530): undefined reference to `wiphy_new_nm'
drivers/built-in.o: In function `wilc_netdev_init':
binder.c:(.text+0x1356d0): undefined reference to `register_inetaddr_notifier'
drivers/built-in.o: In function `linux_spi_init':
binder.c:(.text+0x210a68): undefined reference to `spi_register_driver'

This change ensures that we always have at least one of SPI or MMC
enabled, and are only able to pick an interface that works. It also
adds all the missing dependencies for networking infrastructure
(cfg80211, wext, and ipv4).

In order to make it readable, I also took the liberty of re-indenting
the Kconfig file to the normal conventions.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>