Enable REALTEK_RTL8195AM WiFi

[JanneKiiskila]

Changes needed for the addition of the RTL Wifi-stack to enable REALTEK_RTL8195AM.
README.md also updated.

[bulislaw]

LGTM

[JanneKiiskila]

Test on-going here, ARMmbed/mbed-os-example-client#267

• that is a regression set.

I can't get the RTL WIFI to REALLY work, but it's not an issue in THIS code, IMHO.

[bulislaw]

The wifi example works fine, it doesn't do much, but the connection is established and http transaction is successful : https://github.com/ARMmbed/mbed-os-example-wifi

[JanneKiiskila]

Ok, WiFi now seems to work, there was some temporary (?) problem with our RaaS WiFi (even K64F didn't work for a while). Now it worked, but the actual client connection still failed. Now the Ameba device in CI also got stuck completely, but those are different issues in that sense.

[JanneKiiskila]

Hmh... Killed another device as well in RaaS now (mbed_REALTEK_RTL8195AM#5). Nice.

[janjongboom]

@JanneKiiskila I was on holiday, but should this not be called WIFI_RTL8195. Now we need to rely on Realtek to keep the interface the same for all Realtek drivers...

[JanneKiiskila]

I would be sort of wanting to have less interfaces, rather than more!

[janjongboom]

@JanneKiiskila Yeah, but if Realtek makes a RTL8196 which uses a different driver then we have a problem.

[JanneKiiskila]

We can do a new PR and rename the WIFI_REALTEK to WIFI_RTL8195A. But, I would really want the mbed OS developers to try to cut down on the # of stacks. Even if you have different HW, it doesn't mean you must have different stack!