compat-wireless: fix compilation warning for wl12xx

compat-wireless: fix compilation warning for wl12xx

This should fix this compilation:

  MODPOST 32 modules
WARNING: "wl12xx_get_platform_data"
[/home/mcgrof/tmp/compat/compat-wireless-2.6.39-rc1-2-s/drivers/net/wireless/wl1251/wl1251_sdio.ko] undefined!

This is caused because CONFIG_WL12XX is defined on older
kernels and we need to depend on the platform data
(CONFIG_WL12XX_PLATFORM_DATA) to build CONFIG_WL12XX_SDIO.
Since we cannot disable a config option just rename the config
option.

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>