vga: make Cirrus ISA device optional

Reviewed-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
diff --git a/default-configs/sparc64-softmmu.mak b/default-configs/sparc64-softmmu.mak
index d8f17e7..c9a36c1 100644
--- a/default-configs/sparc64-softmmu.mak
+++ b/default-configs/sparc64-softmmu.mak
@@ -4,7 +4,9 @@
 CONFIG_ISA_MMIO=y
 CONFIG_M48T59=y
 CONFIG_PTIMER=y
+CONFIG_VGA=y
 CONFIG_VGA_PCI=y
+CONFIG_VGA_CIRRUS=y
 CONFIG_SERIAL=y
 CONFIG_PARALLEL=y
 CONFIG_PCKBD=y