hw/ppc/Kconfig: Add dependency PEGASOS2 -> ATI_VGA

The ATI VGA device isn't a requisite for the Pegasos2 machine
because Linux only uses the serial console; see commit ba7e5ac
("hw/ppc: Add emulation of Genesi/bPlan Pegasos II") for rationale.

Using the default devices we don't have any problem:

  $ qemu-system-ppc -M pegasos2
  qemu-system-ppc: standard VGA not available

But when trying to explicitly use the ATI device we get an error:

  $ qemu-system-ppc -M pegasos2 -vga none -bios pegasos2.rom -device ati-vga,romfile=
  qemu-system-ppc: -device ati-vga,romfile=: 'ati-vga' is not a valid device model name

Add it as an implicit Kconfig dependency.

Signed-off-by: Philippe Mathieu-Daudé <[email protected]>
Message-Id: <[email protected]>
Acked-by: BALATON Zoltan <[email protected]>
Reviewed-by: Bin Meng <[email protected]>
Acked-by: David Gibson <[email protected]>

Author: philmd

hw/ppc/Kconfig

@@ -79,6 +79,7 @@ config PEGASOS2
     select VOF
 # This should come with VT82C686
     select ACPI_X86
+    imply ATI_VGA
 
 config PREP
     bool