ARM: imx_v6_v7_defconfig: Enable CONFIG_FB_MXC_LDB

This patch sets CONFIG_FB_MXC_LDB to y so that we may
build in LDB driver.

Signed-off-by: Liu Ying <victor.liu@nxp.com>

arch/arm/configs/imx_v6_v7_defconfig

@@ -317,6 +317,7 @@ CONFIG_FB_MXC_TRULY_PANEL_TFT3P5581E=y
 CONFIG_FB_MXC_RK_PANEL_RK055AHD042=y
 CONFIG_FB_MXC_RK_PANEL_RK055IQH042=y
 CONFIG_FB_MXC_SYNC_PANEL=y
+CONFIG_FB_MXC_LDB=y
 CONFIG_LCD_CLASS_DEVICE=y
 CONFIG_LCD_L4F00242T03=y
 CONFIG_LCD_PLATFORM=y