drm/i915: rename intel_fbc_nuke to intel_fbc_recompress

drm/i915: rename intel_fbc_nuke to intel_fbc_recompress

Although the term "nuke" is part of the FBC spec, it's not very
intuitive, so let's rename it to make it easier for people that are
not familiar with the spec.

Requested-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1446664257-32012-2-git-send-email-paulo.r.zanoni@intel.com
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>