src: Don't include <sys/mount.h> and <linux/mount.h> together

src: Don't include <sys/mount.h> and <linux/mount.h> together

Newer glibc such as glibc 2.36 also defines 'struct mount_attr'
in addition to <linux/mount.h>.

Usually we should use glibc header instead of kernel header.
But now mount.h is a special case because both new glibc header and
kernel header all define "struct mount_attr'. They also define MS*
macro.

Since we have some syscall wrapper in vfs/missing.h, we can use
<linux.mount.h> directly instead of <sys/mount.h> for
detached_mounts_propagation.c.

For utils.c, it doesn't use the macro or function in <sys/mount.h>,
so remove it directly.

In fact, newer glibc(2.37-1)[1] has sloved conflict problem between
<sys/mount.h> and <linux/mount.h>. In the future(maybe ten years), we
can remove this kernel header and use glibc header.

[1]https://sourceware.org/git/?p=glibc.git;a=commit;h=774058d72942249f71d74e7f2b639f77184160a6

Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Yang Xu <xuyang2018.jy@fujitsu.com>
Reviewed-by: Zorro Lang <zlang@redhat.com>
Tested-by: Ziyang Zhang <ZiyangZhang@linux.alibaba.com>
Signed-off-by: Zorro Lang <zlang@kernel.org>