drm/msm: use drm_debug_enabled() to check for debug categories

Allow better abstraction of the drm_debug global variable in the
future. No functional changes.

v2: Move unlikely() to drm_debug_enabled()

Cc: Rob Clark <robdclark@gmail.com>
Cc: Sean Paul <sean@poorly.run>
Cc: linux-arm-msm@vger.kernel.org
Cc: freedreno@lists.freedesktop.org
Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/c7142cdebb5f6fed527272b333cd6c43c0aa68ec.1569329774.git.jani.nikula@intel.com

drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h

@@ -29,7 +29,7 @@
  */
 #define DPU_DEBUG(fmt, ...)                                                \
 	do {                                                               \
-		if (unlikely(drm_debug & DRM_UT_KMS))                      \
+		if (drm_debug_enabled(DRM_UT_KMS))                         \
 			DRM_DEBUG(fmt, ##__VA_ARGS__); \
 		else                                                       \
 			pr_debug(fmt, ##__VA_ARGS__);                      \
@@ -41,7 +41,7 @@
  */
 #define DPU_DEBUG_DRIVER(fmt, ...)                                         \
 	do {                                                               \
-		if (unlikely(drm_debug & DRM_UT_DRIVER))                   \
+		if (drm_debug_enabled(DRM_UT_DRIVER))                      \
 			DRM_ERROR(fmt, ##__VA_ARGS__); \
 		else                                                       \
 			pr_debug(fmt, ##__VA_ARGS__);                      \