x86, olpc: Rework BIOS signature check

The XO-1.5 laptop is not currently detected as an OLPC machine because
it fails this XO-1-centric check.

Now that we have OLPC OFW support in the kernel, a more sensible
check is to see if we found OFW during boot and check the architecture
property.

Also remove a now-meaningless codepath, as we're always going to have
OFW support with OLPC.

Signed-off-by: Daniel Drake <dsd@laptop.org>
LKML-Reference: <20100923162846.D8D409D401B@zog.reactivated.net>
Cc: Andres Salomon <dilinger@queued.net>
Cc: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
diff --git a/arch/x86/include/asm/olpc_ofw.h b/arch/x86/include/asm/olpc_ofw.h
index 08fde47..2a84781 100644
--- a/arch/x86/include/asm/olpc_ofw.h
+++ b/arch/x86/include/asm/olpc_ofw.h
@@ -21,10 +21,14 @@
 /* install OFW's pde permanently into the kernel's pgtable */
 extern void setup_olpc_ofw_pgd(void);
 
+/* check if OFW was detected during boot */
+extern bool olpc_ofw_present(void);
+
 #else /* !CONFIG_OLPC_OPENFIRMWARE */
 
 static inline void olpc_ofw_detect(void) { }
 static inline void setup_olpc_ofw_pgd(void) { }
+static inline bool olpc_ofw_present(void) { return false; }
 
 #endif /* !CONFIG_OLPC_OPENFIRMWARE */