drm/i915: Handle error-state modparams in dedicated functions

Capturing and cleanup and modparams in error state requires
some macro tricks. Move that code into separated functions
for easier maintenance.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20171026173657.49648-3-michal.wajdeczko@intel.com


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