x86, pat: Generalize the use of page flag PG_uncached

Only IA64 was using PG_uncached as of now. We now intend to use this bit
in x86 as well, to keep track of memory type of those addresses that
have page struct for them. So, generalize the use of that bit across
ia64 and x86.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index c07f722..8e15953 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1414,6 +1414,10 @@
 
 	  If unsure, say Y.
 
+config ARCH_USES_PG_UNCACHED
+	def_bool y
+	depends on X86_PAT
+
 config EFI
 	bool "EFI runtime service support"
 	depends on ACPI