lguest: don't try DMI

dmi_scan_machine breaks under lguest; this is the simplest fix (though
ugly).  Perhaps this hurts Xen too?

Error:
	lguest: unhandled trap 14 at 0xc04edeae (0xffa00000)

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
 drivers/firmware/dmi_scan.c |    5 +++++
 1 file changed, 5 insertions(+)

diff -r 47449cd8e3d8 drivers/firmware/dmi_scan.c
--- a/drivers/firmware/dmi_scan.c	Fri Oct 17 12:14:40 2008 +1100
+++ b/drivers/firmware/dmi_scan.c	Fri Oct 17 20:54:30 2008 +1100
@@ -369,6 +369,11 @@ void __init dmi_scan_machine(void)
 	char __iomem *p, *q;
 	int rc;
 
+#ifdef CONFIG_PARAVIRT
+	if (strcmp(pv_info.name, "lguest") == 0)
+		goto error;
+#endif
+
 	if (efi_enabled) {
 		if (efi.smbios == EFI_INVALID_TABLE_ADDR)
 			goto error;