intel/tools/error: Drop support for non-ascii85 encoded error states.

intel/tools/error: Drop support for non-ascii85 encoded error states.

Error state files used to look like:

   render ring --- gtt_offset = 0x0e8f6000
   00000000 :  69040000
   00000004 :  79090000
   ...
   00007ffc :  00000000
   --- ringbuffer = 0x00001000

There were thousands of lines between sections.  The file format changed
with Kernel 4.10, and now has a single ascii85-encoded line following
each section heading.  This is much easier to parse.

There are a bunch of bugs in our handling of the old style format,
where we'd decode the wrong data, at the wrong time.  Fixing all of
these is going to be a giant pain.  It's also a lot of extra code
complexity.  In order to properly decode indirect state, or compute
shaders, we'll also need to parse data in advance of decoding, which
is going to be a giant pain with this ad-hoc "decode everywhere!"
mentality.  So, let's just drop support for the older file format.

This unfortunately requires an error state generated by Kernel 4.10 or
later.  That's probably not the end of the world, as we encourage users
to upgrade to the latest kernel when encountering GPU hangs anyway.  It
might be a giant pain for people with LTS kernels, though...

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>