imxfb: Fix TFT mode

We read from the PCR reg to determine whether to use TFT mode or not.
This is not possible because it may not have been initialized with
the correct value yet. Select it using fbi->pcr instead.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

drivers/video/imxfb.c

@@ -327,7 +327,7 @@ static int imxfb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
 		break;
 	case 16:
 	default:
-		if (readl(fbi->regs + LCDC_PCR) & PCR_TFT)
+		if (fbi->pcr & PCR_TFT)
 			rgb = &def_rgb_16_tft;
 		else
 			rgb = &def_rgb_16_stn;