config: enable ivshmem on POSIX

ivshmem doesn't actually require kvm, so enable it when POSIX is
enabled. (it is required however when ioeventfd is enabled)

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
diff --git a/default-configs/pci.mak b/default-configs/pci.mak
index 7e10903..f250119 100644
--- a/default-configs/pci.mak
+++ b/default-configs/pci.mak
@@ -35,5 +35,5 @@
 CONFIG_EDU=y
 CONFIG_VGA=y
 CONFIG_VGA_PCI=y
-CONFIG_IVSHMEM=$(CONFIG_KVM)
+CONFIG_IVSHMEM=$(CONFIG_POSIX)
 CONFIG_ROCKER=y