ARM: pxa168fb: clear enable bit when not active

While fb isn't active, we should clear CFG_GRA_ENA bit. The existing code
can't clear this bit.

Signed-off-by: Haojian Zhuang <haojian.zhuang@marvell.com>
Acked-by: Marek Vasut <marek.vasut@gmail.com>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>

drivers/video/pxa168fb.c

@@ -298,8 +298,8 @@ static void set_dma_control0(struct pxa168fb_info *fbi)
 	 * Set bit to enable graphics DMA.
 	 */
 	x = readl(fbi->reg_base + LCD_SPU_DMA_CTRL0);
-	x |= fbi->active ? 0x00000100 : 0;
-	fbi->active = 0;
+	x &= ~CFG_GRA_ENA_MASK;
+	x |= fbi->active ? CFG_GRA_ENA(1) : CFG_GRA_ENA(0);
 
 	/*
 	 * If we are in a pseudo-color mode, we need to enable