[SRU][Bionic/raspi2][PATCH] UBUNTU: [Config] Remove upstream mmc modules

[Adam Smith]

>> To switch the mmc driver so close to the release we need a very good
>> reason (or a critical bug).
>> --
>> bye,
>> p.

I've added some more dmesg logs to the bug that show the patch does
NOT switch the mmc drivers that are in use.  The downstream drivers
are the ones in use as far as I can tell.  It is not clear to the
casual viewer what is going on though, which is why I think a clear
config is important.  The patch matches the defconfig and that used by
raspbian/recommended by the raspberry pi foundation.  It is therefore
well tested, certainly more so than the current ubuntu setup.