x86/asm: Use alternative_2() in rdtsc_barrier()

... now that we have it.
Acked-by: NAndy Lutomirski <luto@amacapital.net>
Cc: Richard Weinberger <richard@nod.at>
Signed-off-by: NBorislav Petkov <bp@suse.de>

arch/x86/include/asm/barrier.h

@@ -95,13 +95,11 @@ do {									\
  * Stop RDTSC speculation. This is needed when you need to use RDTSC
  * (or get_cycles or vread that possibly accesses the TSC) in a defined
  * code region.
- *
- * (Could use an alternative three way for this if there was one.)
  */
 static __always_inline void rdtsc_barrier(void)
 {
-	alternative(ASM_NOP3, "mfence", X86_FEATURE_MFENCE_RDTSC);
-	alternative(ASM_NOP3, "lfence", X86_FEATURE_LFENCE_RDTSC);
+	alternative_2("", "mfence", X86_FEATURE_MFENCE_RDTSC,
+			  "lfence", X86_FEATURE_LFENCE_RDTSC);
 }
 
 #endif /* _ASM_X86_BARRIER_H */

arch/x86/um/asm/barrier.h

@@ -64,8 +64,8 @@
  */
 static inline void rdtsc_barrier(void)
 {
-	alternative(ASM_NOP3, "mfence", X86_FEATURE_MFENCE_RDTSC);
-	alternative(ASM_NOP3, "lfence", X86_FEATURE_LFENCE_RDTSC);
+	alternative_2("", "mfence", X86_FEATURE_MFENCE_RDTSC,
+			  "lfence", X86_FEATURE_LFENCE_RDTSC);
 }
 
 #endif