drm/i915: rename intel_fb.c to intel_fbdev.c

This file is all about the legacy fbdev support. If we want to extract
framebuffer functions, we better put those into a separate file.

Also rename functions accordingly, only two have used the intel_fb_
prefix anyway.

Reviewed-by: Chon Ming Lee <chon.ming.lee@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index fd38c37..4a8a2e4 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -10106,14 +10106,14 @@
 }
 
 #ifndef CONFIG_DRM_I915_FBDEV
-static inline void intel_fb_output_poll_changed(struct drm_device *dev)
+static inline void intel_fbdev_output_poll_changed(struct drm_device *dev)
 {
 }
 #endif
 
 static const struct drm_mode_config_funcs intel_mode_funcs = {
 	.fb_create = intel_user_framebuffer_create,
-	.output_poll_changed = intel_fb_output_poll_changed,
+	.output_poll_changed = intel_fbdev_output_poll_changed,
 };
 
 /* Set up chip specific display functions */