x86: fix the missing BIOS area check in page_is_ram

page_is_ram has a FIXME since ages, which reminds to sanity check the
BIOS area between 640k and 1M, which is sometimes falsely reported as
RAM in the e820 tables.

Implement the sanity check. Move the BIOS range defines from
pageattr.c into e820.h to avoid duplicate defines.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 19f7f7a..fcd9612 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -9,18 +9,13 @@
 #include <linux/slab.h>
 #include <linux/mm.h>
 
+#include <asm/e820.h>
 #include <asm/processor.h>
 #include <asm/tlbflush.h>
 #include <asm/sections.h>
 #include <asm/uaccess.h>
 #include <asm/pgalloc.h>
 
-/*
- * We must allow the BIOS range to be executable:
- */
-#define BIOS_BEGIN		0x000a0000
-#define BIOS_END		0x00100000
-
 static inline int
 within(unsigned long addr, unsigned long start, unsigned long end)
 {