MAINTAINERS: remove redundant file of PTRACE SUPPORT entry

In MAINTAINERS PTRACE SUPPORT entry, the file include/uapi/linux/ptrace.h
is redundant, remove it.

Link: https://lkml.kernel.org/r/1649240981-11024-4-git-send-email-yangtiezhu@loongson.cn


Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>