wl1271: the core wl1271 module shouldn't depend on SPI_MASTER

The core wl1271 module can also be used with SDIO, so it should not depend on
SPI_MASTER.

Signed-off-by: Luciano Coelho <luciano.coelho@nokia.com>
Reviewed-by: Juuso Oikarinen <juuso.oikarinen@nokia.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>