x86, mm: fix uninitialized addr in kernel_physical_mapping_init()

This re-adds the lost chunk in commit 9b861528a80.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Haicheng Li <haicheng.li@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
LKML-Reference: <20100903090407.GA19771@localhost>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/mm/init_64.c

@@ -570,6 +570,7 @@ kernel_physical_mapping_init(unsigned long start,
 
 	start = (unsigned long)__va(start);
 	end = (unsigned long)__va(end);
+	addr = start;
 
 	for (; start < end; start = next) {
 		pgd_t *pgd = pgd_offset_k(start);