drm/i915/selftests: Show the pstate limits on any failure to reset min

We want to see the pstate limits whenever we fail to set the minimum
frequency as that may help for debugging.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200420203040.8984-1-chris@chris-wilson.co.uk