x86: trim mtrr don't close gap for resource allocation.

fix the bug reported here:

	http://bugzilla.kernel.org/show_bug.cgi?id=10232

use update_memory_range() instead of add_memory_range() directly
to avoid closing the gap.

( the new code only affects and runs on systems where the MTRR
  workaround triggers. )

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

include/asm-x86/e820_32.h

@@ -28,6 +28,8 @@ extern void find_max_pfn(void);
 extern void register_bootmem_low_pages(unsigned long max_low_pfn);
 extern void add_memory_region(unsigned long long start,
 			      unsigned long long size, int type);
+extern void update_memory_range(u64 start, u64 size, unsigned old_type,
+				unsigned new_type);
 extern void e820_register_memory(void);
 extern void limit_regions(unsigned long long size);
 extern void print_memory_map(char *who);

include/asm-x86/e820_64.h

@@ -18,6 +18,8 @@ extern unsigned long find_e820_area(unsigned long start, unsigned long end,
 				    unsigned size, unsigned long align);
 extern void add_memory_region(unsigned long start, unsigned long size, 
 			      int type);
+extern void update_memory_range(u64 start, u64 size, unsigned old_type,
+				unsigned new_type);
 extern void setup_memory_region(void);
 extern void contig_e820_setup(void); 
 extern unsigned long e820_end_of_ram(void);