wl1271: Moved module basics to wl1271_spi.c

Moved wl1271 drivers probe, remove etc. functions and structres to
wl1271_spi.c from wl1271_main.c in preparation of implementing SDIO interface.

Signed-off-by: Teemu Paasikivi <ext-teemu.3.paasikivi@nokia.com>
Reviewed-by: Juuso Oikarinen <juuso.oikarinen@nokia.com>
Signed-off-by: Juuso Oikarinen <juuso.oikarinen@nokia.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>