video: ARM CLCD: Fix DT-related build problems

This patch fixes the following error when !CONFIG_OF:

drivers/video/fbdev/amba-clcd.c:800:54: warning: ‘struct amba_dev’ declared inside parameter list [enabled by default]
 static struct clcd_board *clcdfb_of_get_board(struct amba_dev *dev)
                                                      ^
and adds a missing Kconfig select causing this
when CONFIG_OF && !CONFIG_FB_MODE_HELPERS:

drivers/video/fbdev/amba-clcd.c:567: undefined reference to `fb_videomode_from_videomode'
Reported-by: NFengguang Wu <fengguang.wu@intel.com>
Signed-off-by: NPawel Moll <pawel.moll@arm.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

drivers/video/fbdev/Kconfig

@@ -280,6 +280,7 @@ config FB_ARMCLCD
 	select FB_CFB_FILLRECT
 	select FB_CFB_COPYAREA
 	select FB_CFB_IMAGEBLIT
+	select FB_MODE_HELPERS if OF
 	select VIDEOMODE_HELPERS if OF
 	help
 	  This framebuffer device driver is for the ARM PrimeCell PL110

drivers/video/fbdev/amba-clcd.c

@@ -797,7 +797,7 @@ static struct clcd_board *clcdfb_of_get_board(struct amba_device *dev)
 	return board;
 }
 #else
-static struct clcd_board *clcdfb_of_get_board(struct amba_dev *dev)
+static struct clcd_board *clcdfb_of_get_board(struct amba_device *dev)
 {
 	return NULL;
 }