x86: enable DEBUG_PAGEALLOC on 64-bit

enable CONFIG_DEBUG_PAGEALLOC=y on 64-bit kernels too.

preliminary testing shows that it's working fine.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

arch/x86/Kconfig.debug

@@ -41,7 +41,6 @@ comment "Page alloc debug is incompatible with Software Suspend on i386"
 config DEBUG_PAGEALLOC
 	bool "Debug page memory allocations"
 	depends on DEBUG_KERNEL && !HIBERNATION && !HUGETLBFS
-	depends on X86_32
 	help
 	  Unmap pages from the kernel linear mapping after free_pages().
 	  This results in a large slowdown, but helps to find certain types