AMD E2 + AMD Radeon R3 problem with Personal Build of PinguyOS 14.04.5

For info on the personal build check here

I have a huge problem with this version and AMD Radeon R3.

Code:

$ lspci -nn | grep -E 'VGA|Display'

00:01.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Mullins [Radeon R3 Graphics] [1002:9850] (rev 40)

Solution, at AskUbuntu forums, seems to be installing a new XServer driver but I got an error.

Code:

$ sudo apt-get install xserver-xorg-video-amdgpu

Reading package lists... Done

Building dependency tree

Reading state information... Done

Note, selecting 'xserver-xorg-video-amdgpu-lts-xenial' instead of 'xserver-xorg-video-amdgpu'

Some packages could not be installed. This may mean that you have

requested an impossible situation or if you are using the unstable

distribution that some required packages have not yet been created

or been moved out of Incoming.

The following information may help to resolve the situation:

The following packages have unmet dependencies.

xserver-xorg-video-amdgpu-lts-xenial : Depends: xorg-video-abi-20

Depends: xserver-xorg-core-lts-xenial (>= 2:1.17.99.902) but it is not going to be installed

E: Unable to correct problems, you have held broken packages.

Antoni suggested to downgrade kernel but:

How do I do it?
What else could become broken afterwards?