x86, kdump: Remove crashkernel range find limit for 64bit

Now kexeced kernel/ramdisk could be above 4g, so remove 896 limit for
64bit.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/1359058816-7615-30-git-send-email-yinghai@kernel.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

arch/x86/kernel/setup.c

@@ -501,13 +501,11 @@ static void __init memblock_x86_reserve_range_setup_data(void)
 /*
  * Keep the crash kernel below this limit.  On 32 bits earlier kernels
  * would limit the kernel to the low 512 MiB due to mapping restrictions.
- * On 64 bits, kexec-tools currently limits us to 896 MiB; increase this
- * limit once kexec-tools are fixed.
  */
 #ifdef CONFIG_X86_32
 # define CRASH_KERNEL_ADDR_MAX	(512 << 20)
 #else
-# define CRASH_KERNEL_ADDR_MAX	(896 << 20)
+# define CRASH_KERNEL_ADDR_MAX	MAXMEM
 #endif
 
 static void __init reserve_crashkernel(void)