video: Make vexpress DVI driver depend on CONFIG_FB

The driver uses symbols from fbmem.c so if CONFIG_FB is not
selected we get build errors like:

drivers/built-in.o: In function `vexpress_dvi_fb_select':
 :(.text+0x1b6c): undefined reference to `lock_fb_info'
 :(.text+0x1ba0): undefined reference to `registered_fb'

Note, this is only a partial solution because we still have a
problem if CONFIG_FB is selected as a module.

Signed-off-by: Jon Medhurst <tixy@linaro.org>
(cherry picked from commit 1a47603600dd0a5579bcfb12dbf084ce170fc234)
Signed-off-by: Alex Shi <alex.shi@linaro.org>
diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
index dade5b7..d9b299f 100644
--- a/drivers/video/Kconfig
+++ b/drivers/video/Kconfig
@@ -39,6 +39,11 @@
 config HDMI
 	bool
 
+config VEXPRESS_DVI_CONTROL
+	bool "Versatile Express DVI control"
+	depends on FB && VEXPRESS_CONFIG
+	default y
+
 menuconfig FB
 	tristate "Support for frame buffer devices"
 	---help---
diff --git a/drivers/video/Makefile b/drivers/video/Makefile
index b005437..7004f7d 100644
--- a/drivers/video/Makefile
+++ b/drivers/video/Makefile
@@ -180,4 +180,4 @@
 endif
 
 # platform specific output drivers
-obj-$(CONFIG_VEXPRESS_CONFIG)	  += vexpress-dvi.o
+obj-$(CONFIG_VEXPRESS_DVI_CONTROL) += vexpress-dvi.o