x86: fix percpu_write with 64-bit constants

Impact: slightly better code generation for percpu_to_op()

The processor will sign-extend 32-bit immediate values in 64-bit
operations.  Use the 'e' constraint ("32-bit signed integer constant,
or a symbolic reference known to fit that range") for 64-bit constants.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

arch/x86/include/asm/percpu.h

@@ -75,7 +75,7 @@ do {							\
 	case 8:						\
 		asm(op "q %1,"__percpu_arg(0)		\
 		    : "+m" (var)			\
-		    : "r" ((T__)val));			\
+		    : "re" ((T__)val));			\
 		break;					\
 	default: __bad_percpu_size();			\
 	}						\