drm/radeon/kms: only warn on mipmap size checks in r600 cs checker (v2)

The texture base address registers are in units of 256 bytes.
The original CS checker treated these offsets as bytes, so the
original check was wrong.  I fixed the units in a patch during
the 2.6.36 cycle, but this ended up breaking some existing
userspace (probably due to a bug in either userspace texture allocation
or the drm texture mipmap checker).  So for now, until we come
up with a better fix, just warn if the mipmap size it too large.
This will keep existing userspace working and it should be just
as safe as before when we were checking the wrong units.  These
are GPU MC addresses, so if they fall outside of the VRAM or
GART apertures, they end up at the GPU default page, so this should
be safe from a security perspective.

v2: Just disable the warning.  It just spams the log and there's
nothing the user can do about it.

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Cc: Jerome Glisse <glisse@freedesktop.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>