mac80211: Make wlcore platform-independent

mac80211: Make wlcore platform-independent

TI wl18xx and wl12xx are Wi-Fi/Bluetooth combo modules
that could be found on different existing boards.

But it is possible to get those modules as a separate
component and use with existing boards as well as
new boards equipped with either module may appear so we
remove dependency on OMAP instead we add dependency on MMC
because this Wi-Fi module uses SDIO interface.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Jo-Philipp Wich <jo@mein.io>
Cc: Felix Fietkau <nbd@nbd.name>
Cc: Imre Kaloz <kaloz@openwrt.org>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>