vga_switcheroo: Depend upon fbcon being built-in, if enabled

Fixes linking fail when fbcon/fbdev is modular and vgaswitcheroo is
enabled:

x86_64-linux-gnu-ld: drivers/gpu/vga/vga_switcheroo.o: in function `vga_switchto_stage2':
vga_switcheroo.c:(.text+0x997): undefined reference to `fbcon_remap_all'

Unfortunately this means that in a default allmodconfig we will disable vgaswitcheroo.

v2: I first tried to fix this with an EXPORT_SYMBOL, but vga_switcheroo is
never a module, so this doesn't work.

Reported-by: Stephen Rothwell <[email protected]>
Reported-by: kbuild test robot <[email protected]>
Fixes: 1cd51b5d20 ("vgaswitcheroo: call fbcon_remap_all directly")
Signed-off-by: Daniel Vetter <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Lukas Wunner <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Sam Ravnborg <[email protected]>
Cc: Maarten Lankhorst <[email protected]>
Cc: David Airlie <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Maxime Ripard <[email protected]>
Cc: Sean Paul <[email protected]>
Cc: Bartlomiej Zolnierkiewicz <[email protected]>
Cc: Hans de Goede <[email protected]>
Cc: Yisheng Xie <[email protected]>
Cc: [email protected]
Cc: Daniel Thompson <[email protected]>
Cc: Lee Jones <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Maarten Lankhorst <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

drivers/gpu/vga/Kconfig

@@ -23,6 +23,7 @@ config VGA_SWITCHEROO
 	depends on X86
 	depends on ACPI
 	depends on PCI
+	depends on (FRAMEBUFFER_CONSOLE=n || FB=y)
 	select VGA_ARB
 	help
 	  Many laptops released in 2008/9/10 have two GPUs with a multiplexer