drm/i915: prefer 3-letter acronym for ironlake

We are currently using a mix of platform name and acronym to name the
functions. Let's prefer the acronym as it should be clear what platform
it's about and it's shorter, so it doesn't go over 80 columns in a few
cases. This converts ironlake to ilk where appropriate.

Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Acked-by: Jani Nikula <jani.nikula@linux.intel.com>
Acked-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191224084012.24241-7-lucas.demarchi@intel.com

drivers/gpu/drm/i915/i915_debugfs.c

@@ -1005,7 +1005,7 @@ static int i915_frequency_info(struct seq_file *m, void *unused)
 	return ret;
 }
 
-static int ironlake_drpc_info(struct seq_file *m)
+static int ilk_drpc_info(struct seq_file *m)
 {
 	struct drm_i915_private *i915 = node_to_i915(m->private);
 	struct intel_uncore *uncore = &i915->uncore;
@@ -1213,7 +1213,7 @@ static int i915_drpc_info(struct seq_file *m, void *unused)
 		else if (INTEL_GEN(dev_priv) >= 6)
 			err = gen6_drpc_info(m);
 		else
-			err = ironlake_drpc_info(m);
+			err = ilk_drpc_info(m);
 	}
 
 	return err;