perf powerpc: Move syscall.tbl check to check-headers.sh

It is better to check syscall.tbl for powerpc in check-headers.sh, it is
similar with commit c9b51a01

 ("perf tools: Move syscall_64.tbl check
into check-headers.sh").

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Xuefeng Li <lixuefeng@loongson.cn>
Link: http://lore.kernel.org/lkml/1608278364-6733-2-git-send-email-yangtiezhu@loongson.cn
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>