framebuffer: disable vgacon on microblaze arch

Fix an allmodconfig link failer on microblaze:
drivers/built-in.o: In function `vgacon_save_screen':
drivers/video/console/.tmp_vgacon.o:(.text+0x8fc10):
undefined reference to `screen_info'

Disable vgacon on microblaze because the symbol
struct screen_info screen_info;
is not defined for the microblaze arch.

---
Note that this patch does not apply to the framebuffer maintainer repo
kernel/git/plagnioj/linux-fbdev.git
listed in MAINTAINERS since that one has not got ee23794b8668 ("video: vgacon: Don't build on arm64").
This prerequisite patch has been merged from
kernel/git/tomba/linux.git fbdev-3.14
into mainline in b788769e0641.

The attached diff applies to both, the mainline tree and Tomi Valkeinen's tree (branch baseline-2015).

 drivers/video/console/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index ba97efc..e0dc0fe 100644
@@ -9,7 +9,7 @@ config VGA_CONSOLE
 	depends on !4xx && !8xx && !SPARC && !M68K && !PARISC && !FRV && \
 		!SUPERH && !BLACKFIN && !AVR32 && !MN10300 && !CRIS && \
 		(!ARM || ARCH_FOOTBRIDGE || ARCH_INTEGRATOR || ARCH_NETWINDER) && \
-		!ARM64
+		!ARM64 && !MICROBLAZE
 	default y
 	help
 	  Saying Y here will allow you to use Linux in text mode through a

2.4.3

Thanks, queued for 4.3.

Tomi