drm/i915: Remove redundant const from function return type

Marking function return types as const is redundant, as these are
rvalues and as such constant by definition. Code checkers and GCC will
warn about this so remove the modifier.
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1463059132-1720-5-git-send-email-imre.deak@intel.com

drivers/gpu/drm/i915/i915_debugfs.c

@@ -89,17 +89,17 @@ static int i915_capabilities(struct seq_file *m, void *data)
 	return 0;
 }
 
-static const char get_active_flag(struct drm_i915_gem_object *obj)
+static char get_active_flag(struct drm_i915_gem_object *obj)
 {
 	return obj->active ? '*' : ' ';
 }
 
-static const char get_pin_flag(struct drm_i915_gem_object *obj)
+static char get_pin_flag(struct drm_i915_gem_object *obj)
 {
 	return obj->pin_display ? 'p' : ' ';
 }
 
-static const char get_tiling_flag(struct drm_i915_gem_object *obj)
+static char get_tiling_flag(struct drm_i915_gem_object *obj)
 {
 	switch (obj->tiling_mode) {
 	default:
@@ -109,12 +109,12 @@ static const char get_tiling_flag(struct drm_i915_gem_object *obj)
 	}
 }
 
-static inline const char get_global_flag(struct drm_i915_gem_object *obj)
+static char get_global_flag(struct drm_i915_gem_object *obj)
 {
 	return i915_gem_obj_to_ggtt(obj) ? 'g' : ' ';
 }
 
-static inline const char get_pin_mapped_flag(struct drm_i915_gem_object *obj)
+static char get_pin_mapped_flag(struct drm_i915_gem_object *obj)
 {
 	return obj->mapping ? 'M' : ' ';
 }