lima: support performance counters

This adds support for querying performance counters on the Mali Utgard
through the GL_AMD_performance_monitor extension.
There are performance counters for the pp, gp and l2 cache cores.

The performance counter event list and descriptions have been retrieved
from ARM's open source "gator" software available in github.

Support for this feature depends on availability of corresponding
patches in the lima kernel driver.

Signed-off-by: Erico Nunes <nunes.erico@gmail.com>