defconfig: msm8960: mdp writeback for 8960

enabling the mdp writeback mode for 8960

Signed-off-by: Nagamalleswararao Ganji <nganji@codeaurora.org>
diff --git a/arch/arm/configs/msm8960_defconfig b/arch/arm/configs/msm8960_defconfig
index d6e14d1..e117ba1 100644
--- a/arch/arm/configs/msm8960_defconfig
+++ b/arch/arm/configs/msm8960_defconfig
@@ -272,6 +272,7 @@
 # CONFIG_FB_MSM_BACKLIGHT is not set
 CONFIG_FB_MSM_MDP40=y
 CONFIG_FB_MSM_OVERLAY=y
+CONFIG_FB_MSM_OVERLAY_WRITEBACK=y
 CONFIG_FB_MSM_MIPI_TOSHIBA_VIDEO_WSVGA_PT_PANEL=y
 CONFIG_FB_MSM_HDMI_MSM_PANEL=y
 CONFIG_BACKLIGHT_LCD_SUPPORT=y