drm/msm/a6xx: Improve a6xx_bus_clear_pending_transactions()

Unify the indentation and explain the cryptic 0xF value.
Reviewed-by: Akhil P Oommen <quic_akhilpo@quicinc.com>
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/542756/Signed-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/adreno/a6xx_gpu.c

@@ -1707,15 +1707,16 @@ static void a6xx_llc_slices_init(struct platform_device *pdev,
 
 #define GBIF_CLIENT_HALT_MASK		BIT(0)
 #define GBIF_ARB_HALT_MASK		BIT(1)
+#define VBIF_XIN_HALT_CTRL0_MASK	GENMASK(3, 0)
 
 void a6xx_bus_clear_pending_transactions(struct adreno_gpu *adreno_gpu, bool gx_off)
 {
 	struct msm_gpu *gpu = &adreno_gpu->base;
 
 	if (!a6xx_has_gbif(adreno_gpu)) {
-		gpu_write(gpu, REG_A6XX_VBIF_XIN_HALT_CTRL0, 0xf);
+		gpu_write(gpu, REG_A6XX_VBIF_XIN_HALT_CTRL0, VBIF_XIN_HALT_CTRL0_MASK);
 		spin_until((gpu_read(gpu, REG_A6XX_VBIF_XIN_HALT_CTRL1) &
-								0xf) == 0xf);
+				(VBIF_XIN_HALT_CTRL0_MASK)) == VBIF_XIN_HALT_CTRL0_MASK);
 		gpu_write(gpu, REG_A6XX_VBIF_XIN_HALT_CTRL0, 0);
 
 		return;