Note that, on the beaglebone, the powervr doesn't drive the display.
Think of it as a headless GPU that have, by itself, no ways to be connected to displays.
It acts merely as a 3D accelerator.

I don't know if it's still true with the version used by Intel for some older platforms.

Here instead you probably lack other drivers to make your display work.

omapfb is probably the driver which you are looking for, but it's already enabled.
I've a GTA04 which now has a working display (it also has an OMAP SOC and a powervr).
You then probably lack some drivers that deals with the HDMI output.

You could look in /proc/config.gz if you see something interesting in that regard.

Denis.