wlcore_sdio/wl18xx: use SDIO revision number to identify wl18xx chips

At least in PG1, the wl18xx chips use the same SDIO vendor/device ID,
so it's not possible to figure out which driver is to be used.  As a
workaround, we can check the SDIO revision number, because wl18xx uses
3.00 and wl12xx does not.

Signed-off-by: Luciano Coelho <coelho@ti.com>
Signed-off-by: Arik Nemtsov <arik@wizery.com>