staging: r8188eu: remove an obsolete comment

Remove an obsolete comment in rtw_dequeue_xframe. There is no break
statement any more.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com> # Edimax N150
Link: https://lore.kernel.org/r/20230123205342.229589-8-martin@kaiser.cx


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