disp: msm: avoid using #ifdef for configurations

Use #if IS_ENABLED() instead of #ifdef for configurations as vendor module
guidelines.

Use #if IS_ENABLED(CONFIG_XXX) instead of #ifdef CONFIG_XXX to ensure that
the code inside the #if block continues to compile if the config changes
to a tristate config in the future.

The differences are as follows:
	1.#if IS_ENABLED(CONFIG_XXX) evaluates to true when CONFIG_XXX is set to
		module (=m) or built-in (=y).
	2.#ifdef CONFIG_XXX evaluates to true when CONFIG_XXX is set to
		built-in(=y) , but doesn't when CONFIG_XXX is set to module(=m).
		Use this only when you're certain you want to do the same thing
		when the config is set to module or is disabled.

Change-Id: Ia806b9b01ad8414d0e4de027a382cb68e7fb4a6a
Signed-off-by: GG Hou <quic_renjhou@quicinc.com>

msm/msm_drv.h

@@ -1302,7 +1302,7 @@ static inline void __exit msm_mdp_unregister(void)
 }
 #endif /* CONFIG_DRM_MSM_MDP5 */
 
-#ifdef CONFIG_DEBUG_FS
+#if IS_ENABLED(CONFIG_DEBUG_FS)
 int msm_debugfs_late_init(struct drm_device *dev);
 int msm_rd_debugfs_init(struct drm_minor *minor);
 void msm_rd_debugfs_cleanup(struct msm_drm_private *priv);
@@ -1318,7 +1318,7 @@ static inline void msm_rd_dump_submit(struct msm_rd_state *rd, struct msm_gem_su
 		const char *fmt, ...) {}
 static inline void msm_rd_debugfs_cleanup(struct msm_drm_private *priv) {}
 static inline void msm_perf_debugfs_cleanup(struct msm_drm_private *priv) {}
-#endif
+#endif /* CONFIG_DEBUG_FS */
 
 #if IS_ENABLED(CONFIG_DRM_MSM_DSI)
 void __init dsi_display_register(void);