um: allow disabling NO_IOMEM

Adjust the kconfig a little to allow disabling NO_IOMEM in UML. To
make an "allyesconfig" with CONFIG_NO_IOMEM=n build, adjust a few
Kconfig things elsewhere and add dummy asm/fb.h and asm/vga.h files.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
diff --git a/drivers/tty/Kconfig b/drivers/tty/Kconfig
index f6a7fd6..5b0736f 100644
--- a/drivers/tty/Kconfig
+++ b/drivers/tty/Kconfig
@@ -12,9 +12,8 @@
 
 config VT
 	bool "Virtual terminal" if EXPERT
-	depends on !UML
 	select INPUT
-	default y
+	default y if !UML
 	help
 	  If you say Y here, you will get support for terminal devices with
 	  display and keyboard devices. These are called "virtual" because you
@@ -78,7 +77,7 @@
 
 config HW_CONSOLE
 	bool
-	depends on VT && !UML
+	depends on VT
 	default y
 
 config VT_HW_CONSOLE_BINDING