wl1271: fix sdio driver name in wl1271_sdio_driver

Our SPI driver is called "wl1271_spi" in the driver information structure.
Let's use the same for SDIO so that things are aligned.

Signed-off-by: Luciano Coelho <luciano.coelho@nokia.com>
Reviewed-by: Teemu Paasikivi <ext-teemu.3.paasikivi@nokia.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>