x86: rename two e820 related functions

rename update_memory_range to e820_update_range
rename add_memory_region to e820_add_region

to make it more clear that they are about e820 map operations.

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index 82517e4..9001c9d 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -39,8 +39,8 @@
 	unsigned long max_pfn = xen_start_info->nr_pages;
 
 	e820.nr_map = 0;
-	add_memory_region(0, LOWMEMSIZE(), E820_RAM);
-	add_memory_region(HIGH_MEMORY, PFN_PHYS(max_pfn)-HIGH_MEMORY, E820_RAM);
+	e820_add_region(0, LOWMEMSIZE(), E820_RAM);
+	e820_add_region(HIGH_MEMORY, PFN_PHYS(max_pfn)-HIGH_MEMORY, E820_RAM);
 
 	return "Xen";
 }