USB: core: remove the move buf action

The buffer size of sysfs is fixed at PAGE_SIZE, and the page offset
of the buf parameter of sysfs_emit_at() must be 0, there is no need
to manually manage the buf pointer offset.

Fixes: 711d41ab ("usb: core: Use sysfs_emit_at() when showing dynamic IDs")
Reported-by:  <syzbot+b6445765657b5855e869@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=b6445765657b5855e869


Tested-by:  <syzbot+b6445765657b5855e869@syzkaller.appspotmail.com>
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
Link: https://lore.kernel.org/r/tencent_B32D6D8C9450EBFEEE5ACC2C7B0E6C402D0A@qq.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>