x86/percpu: Remove "e" constraint from XADD

The "e" constraint represents a constant, but the XADD instruction doesn't
accept immediate operands.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Dennis Zhou <dennis@kernel.org>
Link: https://lkml.kernel.org/r/20200720204925.3654302-6-ndesaulniers@google.com

arch/x86/include/asm/percpu.h

@@ -220,7 +220,7 @@ do {									\
 		break;							\
 	case 8:								\
 		asm qual ("xaddq %0, "__percpu_arg(1)			\
-			    : "+re" (paro_ret__), "+m" (var)		\
+			    : "+r" (paro_ret__), "+m" (var)		\
 			    : : "memory");				\
 		break;							\
 	default: __bad_percpu_size();					\