wl1271: remove warnings in wl1271_sdio_set_power

These were introduced in "wl1271: sdio: claim host only when doing IO"

drivers/net/wireless/wl12xx/wl1271_sdio.c: In function ‘wl1271_sdio_set_power’:
drivers/net/wireless/wl12xx/wl1271_sdio.c:193: warning: ‘return’ with a value, in function returning void
drivers/net/wireless/wl12xx/wl1271_sdio.c:195: warning: ‘return’ with a value, in function returning void
drivers/net/wireless/wl12xx/wl1271_sdio.c:186: warning: unused variable ‘func’

Signed-off-by: John W. Linville <linville@tuxdriver.com>