perf/bench: Fix mem* routines usage after alternatives change

Adjust perf bench to the new changes in the alternatives code for
memcpy/memset.

Reviewed-by: Hitoshi Mitake <mitake.hitoshi@lab.ntt.co.jp>
Signed-off-by: Borislav Petkov <bp@suse.de>

tools/perf/util/include/asm/alternative-asm.h

@@ -4,5 +4,6 @@
 /* Just disable it so we can build arch/x86/lib/memcpy_64.S for perf bench: */
 
 #define altinstruction_entry #
+#define ALTERNATIVE_2 #
 
 #endif