perf tools: Make the x86 clean quiet

Turn current clean output:

$ make clean
rm -f arch/x86/include/generated/asm/syscalls_64.c
CLEAN libbpf
CLEAN libapi

into:

$ make clean
CLEAN x86
CLEAN libapi
CLEAN libbpf

Signed-off-by: Jiri Olsa <[e-mail]>
Tested-by: Arnaldo Carvalho de Melo <[e-mail]>
Cc: David Ahern <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: TJ <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/arch/x86/Makefile

···
 	$(Q)$(SHELL) '$(systbl)' $(sys)/syscall_64.tbl 'x86_64' > $@
 
 clean::
-	rm -f $(header)
+	$(call QUIET_CLEAN, x86) $(RM) $(header)
 
 archheaders: $(header)